1st

Semester Review - EXAMINATION October –November -2014

Curriculum: MYP

1 | P a g e

SUBJECT / PAPER: PHYSICS

DATE 7 Nov CRITERIA A, B, C, D DURATION 2 Hrs. CLASS &

SEC 8MYP

General Instructions

• Do not start the paper until instructed.

• Mention the question number on the answer scripts clearly.

• Use of calculators is allowed.

• Use Black or Blue ballpoint pen only to write your answers.

• For Diagrams/ Drawings use pencil.

• Use of unfair means in any form may lead to cancellation of current paper or all.

• Students are allowed to leave the examination hall only after the end of examination.

• At the end of the examination, fasten all your work securely together.

Criterion Achievement

level

Level descriptor

Cri

teri

on

A K

no

win

g a

nd

un

der

san

din

g

0 • The student does not reach a standard described by any of the descriptors below.

1 – 2

• The student is able to: i recall scientific knowledge

ii apply scientific knowledge and understanding to suggest solutions to problems

set in familiar situations

iii apply information to make judgments.

3 – 4

• The student is able to: i state scientific knowledge

ii apply scientific knowledge and understanding to solve problems set in familiar

situations iii apply information to make scientifically supported judgments.

5 – 6

• The student is able to: i outline scientific knowledge

ii apply scientific knowledge and understanding to solve problems set in familiar

situations and suggest solutions to problems set in unfamiliar situations

iii interpret information to make scientifically supported judgments.

7 – 8

• The student is able to: i describe scientific knowledge

ii apply scientific knowledge and understanding to solve problems set in familiar

and unfamiliar situations iii analyse information to make scientifically supported judgments.

Lev

el

ach

ieved

2 | P a g e

A.(i).1 recall scientific knowledge

1. Match the following by drawing straight lines.

Particle name Charge

1. Proton Positive

2. electron Neutral

3. neutron negative

2. Opposite charges ____________________ [attract/repel].

3. The object which gains electrons has ___________________ charge. [positive/negative]

4. Metals are described as ___________________ [conductors/insulators] because they

__________________ [allow/ do not allow] electricity to pass through them.

5. Match the following by drawing straight lines.

Circuit component Name of circuit component Symbol of circuit component

Electric bulb

Electric cell

battery

Switch in ‘ON’ position

wire

Switch in ‘OFF’ position

3 | P a g e

6. Choose the correct answer by ticking the correct choice.

(i) Which shows the correct way to use an ammeter?

A.(i).2 state scientific knowledge

7. Fill in the blanks.

(i) Ammeter measures ____________________. Its unit is ______________ and symbol of the unit is

___________.

(ii) Voltmeter measures ___________________. Its unit is ______________ and symbol of the unit is

____________.

(iii) ____________________ is a device that can show whether an object has positive or negative

charge.

8. What type of circuit is described by each of the following statements? Answer ‘series’ or ‘parallel’.

(i) All components are connected end-to-end. _____________________

(ii) The current in the circuit divides so that some flows through one component and the rest through

another component. ________________________

(iii) Two identical lamps are connected side by side so that each lights brightly.________________

(iv) The current has the same value everywhere in the circuit.___________________________

A.(i).3 outline scientific knowledge

9. What are the rules of attraction and repulsion of charges?

…………………………………………………………………………………………………………

…………………………………………………………………………………………………………

………………………………………………………………………………………………………….

…………………………………………………………………………………………………………

4 | P a g e

…………………………………………………………………………………………………………

10. Two balls are hanging as shown in the figure.

(i) What would happen if both the balls acquired positive charge?

…………………………………………………………………

………………………………………………………………….

(ii) What would happen if both the balls acquired negative charge?

………………………………………………………………….

………………………………………………………………….

(iii) What would happen if one of the balls acquired positive charge and

the other ball acquired negative charge?

………………………………………………………………….

………………………………………………………………….

A.(i).4 describe scientific knowledge

11. Answer the following questions based on the diagram given below, which indicate the charges

present after an electrically neutral rod and cloth were rubbed together.

(a) Describe in detail how the

polythene rod and woolen cloth

become charged when they are

rubbed together. Mention how

and why the charge transfer take

place between the rod and the

cloth.

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

5 | P a g e

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

(b) Describe in detail how the

acrylic rod and cotton cloth

become charged when they are

rubbed together. Mention how

and why the charge transfer take

place between the rod and the

cloth.

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

12. What does the current from the battery do when it meets a junction (junction is a place where two or

more wires meet) in a parallel circuit?

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

6 | P a g e

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

13. Explain why it is better to wire house lights in parallel.

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

A.(ii).1 apply scientific knowledge and understanding to suggest solutions to/solve problems set in

familiar situations

14. Choose the correct answer by ticking the correct choice.

(i) If you increase the voltage of the battery, how will the light bulb change?

A. It will look brighter because the yellow lines are brighter and longer

B. It will be less bright because the yellow lines are less bright and

shorter

C. There is no change because the bulb just uses the extra energy

without changing brightness.

7 | P a g e

(ii) If you build circuit A and then add a resistor as in circuit B, the light will

A. look brighter

B. look less bright

C. there will be no change in brightness

(iii) Answer the following questions based on the circuit diagram given below:

(a) Which resistor will have the greatest current?

A. the 50 Ω resistor

B. the 10 Ω resistor

C. both resistors have the same current

(b) Which resistor will have the greatest voltage?

A. the 50 Ω resistor

B. the 10 Ω resistor

C. both resistors have the same voltage

(iv) Answer the following questions based on the circuit diagram given below:

(a) Which resistor will have the greatest current?

A. the top resistor

B. the bottom resistor

C. both resistors have the same current

(b) Which resistor will have the greatest voltage?

A. the top resistor

B. the bottom resistor

C. both resistors have the same voltage

(v) Answer the following questions based on the circuit diagram given below:

(a) Which resistor will have the greatest current?

A. the 50 Ω resistor

B. the 10 Ω resistor

C. both resistors have the same current

(b) Which resistor will have the greatest voltage?

A. the 50 Ω resistor

B. the 10 Ω resistor

C.both resistors have the same voltage

8 | P a g e

(vi) Answer the following questions based on the circuit diagram given below:

(a) Which resistor will have the greatest current?

A. the top resistor

B. the bottom resistor

C. both resistors have the same current

(b) Which resistor will have the greatest voltage?

A. the top resistor

B. the bottom resistor

C. both resistors have the same voltage

(vii) Choose the correct options based on the diagram given below. More than one option could be

correct. So select ALL correct options.

What will happen if the voltage of the cell is increased to 20 V?

A. the voltage across the resistor will increase

B. the voltage across the resistor will decrease

C. the voltage across the resistor does not change

D. the current through the resistor will increase

E. the current through the resistor will decrease

F. the current through the resistor does not change

(viii) What is the total resistance in the following circuits?

(a)

A. 6.4 Ω

B. 21 Ω

C. 38 Ω

D. 75 Ω

9 | P a g e

(b)

A. 6.4 Ω

B. 21 Ω

C. 38 Ω

D. 75 Ω

A.(ii).1 apply scientific knowledge and understanding to suggest solutions to / solve problems set

in unfamiliar situations

15. Dimmer switches change the brightness of lights. A variable resistance is used to change the

resistance in a circuit. Variable resistors often have a control knob to change the value of the resistance.

Volume controls are made from variable resistors.

A dimmer switch uses a variable resistor. Thus, by turning the dimmer switch, you change the

resistance. When you turn the dimmer switch clockwise, it decreases the resistance. When you turn the

dimmer switch anticlockwise, it increases the resistance. You can observe this in the diagram below.

(a) Explain what happens (and why) to the brightness of the light bulb when you turn the dimmer switch

clockwise.

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

10 | P a g e

…………………………………………………………………………………………………………..

(b) Explain what happens (and why) to the brightness of the light bulb when you turn the dimmer switch

anticlockwise.

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

(c) Explain what happens (and why) to the brightness of the light bulbs when you add more bulbs in

series to the circuit.

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

(d) Explain what happens (and why) to the brightness of the light bulbs when you add more bulbs in

parallel to the circuit.

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

11 | P a g e

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

…………………………………………………………………………………………………………..

16. The flow of electric current around a circuit is like the flow of water around a system of pipes. The

cell or battery is like the pump. An ammeter in the electrical circuit is like a paddle wheel that turns and

tells you how fast the water flows in the pipes. An ammeter measures the flow of electric current in

amperes. Look at the diagram below which compares an electric circuit to a water circuit and fill in the

blanks in the following tables.

electric circuit water circuit

component of electric

circuit

job component of water

circuit

job

……………………..

pushes the current

around the circuit

……………………..

pushes the water

through the pipes

charge flows around the circuit

……………………..

flows around the pipes

ammeter shows higher value if

more charge crosses it

every second

……………………..

rotates faster if more

water passes through it

every second

……………………..

can break the circuit

and stop the flow of

current

……………………..

can stop the flow of

water

12 | P a g e

A.(iii).1 apply information to make scientifically supported judgements

17. Electricity will flow ONLY when a circuit is complete. The following four diagrams show four

attempts at making a light bulb light up. Explain WHY each attempt will WORK or NOT WORK.

(a)

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

(b)

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

13 | P a g e

(c)

note: the circuit is connected using wooden sticks

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

(d)

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

…………………………………………………

14 | P a g e

A.(iii).2 interpret information to make scientifically supported judgements

18.

15 | P a g e

(b)

A.(iii).3 analyse information to make scientifically supported judgements

19. Read this information taken from a recent newspaper article.

• Researchers have found that children living close to overhead power cables are more likely to

develop leukaemia (blood cancer).

• The researchers studied two groups of children. One group had developed leukaemia, the other

group was healthy.

• Although the researchers found a link, they are unable to explain why some children got

leukaemia. They say that the results may have happened by chance.

• Other factors that have not been investigated, such as the environment, the geographical area or

the children’s genes, could be important.

• A cancer research charity said that childhood leukaemia was most likely to be caused by factors

that parents were unable to control.

(a) Why did researchers study a group of healthy children?

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

16 | P a g e

(b) The information does not say how many children were studied. Why should this data have been

included in the article?

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

(c) The researchers could not be certain that the overhead power cables were responsible for the

increased chance of children developing leukaemia. Explain why.

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

(d) The results of the research carried out by scientists may worry some people.

What do you think scientists should do?

Put a () in the box next to your choice.

Scientists should (i) publish their research findings straight away.

(ii) not publish their research findings until they have found out as many facts as possible. Give a reason for your choice.

……………………………………………………………………………………………………………..

……………………………………………………………………………………………………………..

……………………………………………………………………………………………………………..

17 | P a g e

……………………………………………………………………………………………………………..

……………………………………………………………………………………………………………..

……………………………………………………………………………………………………………..

Criterion Achievement

level

Level descriptor

Cri

teri

on

B I

nq

uir

ing

an

d D

esig

nin

g

0 • The student does not reach a standard described by any of the descriptors below.

1 – 2

• The student is able to: i state a problem or question to be tested by a scientific investigation, with limited

success ii state a testable hypothesis

iii state the variables iv design a method, with limited success.

3 – 4

• The student is able to:

i state a problem or question to be tested by a scientific investigation

ii outline a testable hypothesis using scientific reasoning iii outline how to manipulate the variables, and state how relevant data will be

collected iv design a safe method in which he or she selects materials and equipment.

5 – 6

• The student is able to:

i outline a problem or question to be tested by a scientific investigation

ii outline and explain a testable hypothesis using scientific reasoning iii outline how to manipulate the variables, and outline how sufficient, relevant

data will be collected iv design a complete and safe method in which he or she selects appropriate

materials and equipment.

7 – 8

• The student is able to:

i describe a problem or question to be tested by a scientific investigation ii outline and explain a testable hypothesis using correct scientific reasoning

iii describe how to manipulate the variables, and describe how sufficient, relevant data will be collected

iv design a logical, complete and safe method in which he or she selects appropriate materials and equipment.

Lev

el A

chie

ved

18 | P a g e

B.(i) state/outline/describe a problem or question to be tested by a scientific investigation

20. You are given an ammeter to measure current, a voltmeter to measure potential difference, a cell

whose voltage can be varied, a resistance box whose resistance can be set to any value, connecting wires,

and a key.

Frame a research question of the form “How does Y depend on X?” Where Y and X are any of the

parameters like current, resistance and potential difference across the resistance.

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

B.(ii) state/outline/explain a testable hypothesis using scientific reasoning

21. For the above research question which you created, explain a testable hypothesis with scientific

reasoning. How do you expect whatever you chose as ‘Y’ to vary with whatever you chose as ‘X’? How will

you test it by doing an experiment?

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

……………………………………………………………………………………………………………

19 | P a g e

B.(iii).1 state the variables

22. For the above research question,

(a) what will be your independent variable?

………………………………………………………………………………………………………….

(b) what will be your dependent variable?

………………………………………………………………………………………………………….

(c) what will be your control variables?

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

20 | P a g e

B.(iii).2 outline/describe how to manipulate the variables and state/outline/describe how sufficient,

relevant data will be collected

23. For the above research question, fill the blanks in the column headings and write suitable values for the

second column (independent variable).

S. No

[Independent variable name], [variable

symbol] / [symbol of unit of variable]

[………………………………………..],[………….] /

[………………]

[dependent variable name], [variable symbol] /

[symbol of unit of variable]

[………………………………………..],[………….] /

[………………]

trial 1 trial 2 trial 3 mean

1

2

3

4

5

6

7

8

9

10

B.(iv) design a logical, complete and safe method in which he or she selects appropriate materials and

equipment

24. Describe how you will conduct the experiment to take the measurements to collect the data for the

dependent variable to fill the above observation table.

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

21 | P a g e

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

…………………………………………………………………………………………………………………

22 | P a g e

Criterion Achievement

level

Level descriptor C

rite

rio

n C

Pro

cess

ing

an

d E

va

lua

tin

g

0 • The student does not reach a standard described by any of the descriptors below.

1 – 2

• The student is able to: i collect and present data in numerical and/or visual forms ii accurately interpret data iii state the validity of a hypothesis with limited reference to a scientific investigation iv state the validity of the method with limited reference to a scientific investigation v state limited improvements or extensions to the method.

3 – 4

• The student is able to:

i correctly collect and present data in numerical and/or visual forms ii accurately interpret data and describe results iii state the validity of a hypothesis based on the outcome of a scientific investigation iv state the validity of the method based on the outcome of a scientific investigation v state improvements or extensions to the method that would benefit the scientific

investigation.

5 – 6

• The student is able to:

i correctly collect, organize and present data in numerical and/or visual forms

ii accurately interpret data and describe results using scientific reasoning iii outline the validity of a hypothesis based on the outcome of a scientific investigation

iv outline the validity of the method based on the outcome of a scientific investigation v outline improvements or extensions to the method that would benefit the scientific

investigation.

7 – 8

• The student is able to:

i correctly collect, organize, transform and present data in numerical and/or visual forms

ii accurately interpret data and describe results using correct scientific reasoning

iii discuss the validity of a hypothesis based on the outcome of a scientific investigation iv discuss the validity of the method based on the outcome of a scientific investigation v describe improvements or extensions to the method that would benefit the scientific

investigation.

Lev

el A

chie

ved

C.(i) correctly collect, organize, transform and present data in numerical and/or visual forms

25. The following table gives the raw data collected after measuring the current through a given resistor

for different values of potential difference across it.

S.No potential difference across the resistor, V / V current, I / A

1 0 0.00

2 1 0.25

3 2 0.50

4 3 0.75

5 4 1.00

6 5 1.25

7 6 1.50

8 7 1.75

9 8 2.00

10 9 2.25

Plot the graph of current (on vertical axis) vs potential difference (on horizontal axis) in the graph below.

Remember to label the axes of the graph with variable name, unit and

cover as much area of the graph as possible.

Draw a best-fit straight line through the data points.

C.(ii) accurately interpret data and describe results using correct scientific reasoning

26. What is the slope of the above graph? Show your calculations and write the units of the slope.

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

23 | P a g e

Plot the graph of current (on vertical axis) vs potential difference (on horizontal axis) in the graph below.

Remember to label the axes of the graph with variable name, unit and symbol. The data points should

cover as much area of the graph as possible.

fit straight line through the data points.

C.(ii) accurately interpret data and describe results using correct scientific reasoning

ve graph? Show your calculations and write the units of the slope.

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

Plot the graph of current (on vertical axis) vs potential difference (on horizontal axis) in the graph below.

symbol. The data points should

C.(ii) accurately interpret data and describe results using correct scientific reasoning

ve graph? Show your calculations and write the units of the slope.

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

………………………………………………………………………………………………………….

24 | P a g e

C.(iii) state/outline/discuss the validity of a hypothesis based on the outcome of a scientific

investigation

27. Does the calculated value of the slope, support the hypothesis that the unknown resistance must be

0.25 Ω?

…………………………………………………………………………………………………………

28. Does the graph support the hypothesis that the unknown resistance is constant and does not depend

on the potential difference applied across it?

…………………………………………………………………………………………………………….

…………………………………………………………………………………………………………….

29. To what extent is the hypothesis correct? Explain which part of the hypothesis may be right or

wrong.

……………………………………………………………………………………………………………..

…………………………………………………………………………………………………………….

…………………………………………………………………………………………………………….

…………………………………………………………………………………………………………….

…………………………………………………………………………………………………………….

…………………………………………………………………………………………………………….

…………………………………………………………………………………………………………….

C.(iv) state/outline/discuss the validity of a method based on the outcome of a scientific

investigation

30. The above experiment was performed using the Phet simulation. Is it practically possible to change

the potential difference provided by a cell, as was done in the phet simulation?

……………………………………………………………………………………………………………

C.(v) state/outline/describe improvements or extensions to the method that would benefit the

scientific investigation

31. Suggest how you can change the potential difference across the resistance without changing the cell.

What modification do you have to make to the circuit? Draw the circuit diagram in the space below.

……………………………………………………………………………………………………………..

25 | P a g e

…………………………………………………………………………………………………………….

…………………………………………………………………………………………………………….

…………………………………………………………………………………………………………….

…………………………………………………………………………………………………………….

…………………………………………………………………………………………………………….

…………………………………………………………………………………………………………….

Criterion Achievement

level

Level descriptor

Cri

teri

on

D R

efle

ctin

g o

n t

he

imp

act

s o

f S

cien

ce

0 • The student does not reach a standard described by any of the descriptors below.

1 – 2

• The student is able to:

i state the ways in which science is used to address a specific problem or issue ii state the implications of the use of science to solve a specific problem or issue,

interacting with a factor

iii apply scientific language to communicate understanding but does so with limited success

iv document sources, with limited success.

3 – 4

• The student is able to:

i outline the ways in which science is used to address a specific problem or issue ii outline the implications of using science to solve a specific problem or issue,

interacting with a factor iii sometimes apply understanding scientific language to communicate

iv sometimes document sources correctly.

5 – 6

• The student is able to:

i summarize the ways in which science is applied and used to address a specific problem or issue

ii describe the implications of using science and its application to solve a specific problem or issue, interacting with a factor

iii usually apply scientific language to communicate understanding clearly and precisely

iv usually document sources correctly.

7 – 8

• The student is able to:

i describe the ways in which science is applied and used to address a specific problem or issue

ii discuss and analyse the implications of using science and its application to solve a specific problem or issue, interacting with a factor

iii consistently apply scientific language to communicate understanding clearly and precisely

iv document sources completely.

Lev

el A

chie

ved

26 | P a g e

D.(i) state/outline/summarize/describe the ways in which science is applied and used to address a specific

problem or issue

32. Power stations produce electricity in large quantities to meet the requirements of the population in a city. But

the power stations also produce a lot of pollution and are a hazard for the population. So power stations are usually

set up very far away from the residential areas for safety purposes. This creates the problem of transporting the

electrical energy to the people living in the cities who need to use it. Describe the ways in which science is applied to

solve this problem. Use the picture clue given below.

…………………………………………………………………………………………………………………….

…………………………………………………………………………………………………………………….

…………………………………………………………………………………………………………………….

…………………………………………………………………………………………………………………….

…………………………………………………………………………………………………………………….

…………………………………………………………………………………………………………………….

…………………………………………………………………………………………………………………….

…………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………………………………..

……………………………………………………………………………………………………………………………………………………………………………………..

33. Before the discovery of the light bulb, people used to depend on burning of fuel to produce light. This used to

produce less light and caused pollution. After the discovery of electricity, many researchers tried to produce light by

passing electricity through different materials so that they became red hot or white hot and emitted light by

glowing. But they faced the problem that the materials soon caught fire and burned completely, almost immediately

after they started glowing and emitting light. How did Edison apply science to solve this problem? Explain in detail.

……………………………………………………………………………………………………………………………………………………………………………………..

……………………………………………………………………………………………………………………………………………………………………………………..

27 | P a g e

……………………………………………………………………………………………………………………………………………………………………………………..

……………………………………………………………………………………………………………………………………………………………………………………..

……………………………………………………………………………………………………………………………………………………………………………………..

……………………………………………………………………………………………………………………………………………………………………………………..

……………………………………………………………………………………………………………………………………………………………………………………..

……………………………………………………………………………………………………………………………………………………………………………………..

……………………………………………………………………………………………………………………………………………………………………………………..

……………………………………………………………………………………………………………………………………………………………………………………..

……………………………………………………………………………………………………………………………………………………………………………………..

34. Since the fluorescent tubes and the incandescent light bulbs consume lot of electricity to produce the bright

light, researchers have been trying to find a more efficient source of light energy. This year’s Nobel Prize in physics

was awarded to the following three people:

for the invention of efficient ……………………………………………………………………………………………. which has enabled bright

and energy-saving white light sources.

28 | P a g e

D.(ii) state/outline/describe/discuss and analyse the implications of using science and its application to solve a

specific problem or issue, interacting with a factor.

35. People need electricity to power all their electrical devices. So electricity needs to be supplied to homes at high

voltages (around 220 V) to meet the electricity requirements. Science has solved this problem by the use of high

voltage transmission with the help of transformers and electric cables. But high voltage electricity is dangerous since

it can cause fire. Read the following news clipping from the Times of India to get an idea about the dangers of using

electricity without adequate safety measures.

Mumbai has most short-circuit fires and deaths in India

Mumbai is the most dangerous city in the country as far as fires caused by short-circuit go. From 2009 to 2013, 285 short-circuit-caused fires occurred in Maharashtra's capital city, compared to 196 in Delhi, which is second on a list released by the National Crime Records Bureau (NCRB) a little over a month ago. The incidents, brought into focus because of Friday's Vashi hotel and Thane coaching class fires, were reported from commercial and residential buildings. Experts say short-circuits usually occur because people use poor equipment or do not maintain them.

Fire brigade and police officers say short-circuit is mainly caused by the use of electrical equipment

of poor quality. They say that despite safe-practice campaigns on TV and in newspapers, most people

ignore instructions. "Most short-circuit-caused fires begin in air-conditioners or power mains. Even

if people buy quality equipment, they don't maintain them, leading to deterioration in the quality of

wire coverings. Overloading of lines is another cause," said a fire officer.

"Poor maintenance leads to erosion of the coatings of wires, making them exposed. A short-circuit is

caused when such wires carrying electricity come in contact," said Mumbai's deputy chief fire officer

P S Rahangdale.

Another reason is littering of ducts and dumping waste in areas close to electrical equipment or

wires. "Waste paper and such matter easily catch and spread fire. Again, many buildings don't have

garbage corners, encouraging people to litter," said the officials.

As for casualties, "the majority of deaths is caused due to panicking and suffocation", said

Rahangdale.

As for prevention, experts suggest various precautions, including not allowing AC ducting to pass

through floors. "Fire, heat and smoke travel through ducts and spread to other parts of a building.

So, it is important to sectionalize them," said an expert. "This should be done, as far as practical, even

on individual floors to limit the spread of fire, heat and smoke, minimising damage."

Based on the above news clipping, answer the following questions regarding the problem of how to use

electricity safely and prevent any accidents caused by electricity.

(a) Explain what happens if we use electricity without understanding it, and without following any safety

measures. Give examples.

29 | P a g e

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

(b) Which is the most dangerous city in India because of fires caused by short-circuits? Support your

answer with facts.

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

30 | P a g e

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

(c) Where do most short-circuit fires begin?

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

(d) What are the two main causes of short-circuit fires?

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

31 | P a g e

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

(e) Why is it dangerous to litter near ducts and areas close to electrical equipment and wires?

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

32 | P a g e

(f) What is the major cause of death in fires caused by short-circuits?

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

(g) What precaution can be taken while constructing houses to limit the spread of fire, heat and smoke in

the event of a fire caused by short-circuit?

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

……………………………………………………………………………………………………………………………………………………………….

*******************************************THE END************************************