Year 7 Phase 3 - Ark Globe Academy 7 Science Work Pack Pha… · 2. Check for understanding and...

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Year 7 Phase 3 SCIENCE WORKBOOK

Name: ___________________________________________________

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Session Title Work to be completed

Resource provided

Outcome On-Line Support

1 Static Electricity and Atomic structure

DO NOW Apply tasks

Phase III Workbook with tasks Pages 4-7

Completed: 1.DO NOW 2. Check for understanding and apply tasks

Session 1 + 2 Static electricity and atomic structure lesson on VLE

2 Static Electricity and Atomic structure

Do Now Apply tasks


Completed: 1.DO NOW 2. Apply tasks

See above

3 Circuits DO NOW Apply tasks


Completed: 1.DO NOW 2. Check for understanding and apply tasks

Session 3 + 4 Circuits lesson on VLE

4 Circuits Do Now Apply tasks

Phase III Workbook with tasks Pages 15- 23


See above

5 Current DO NOW Check for Understanding Task


Completed: 1.DO NOW 2.Check for Understanding Task

Session 5 + 6 Current lesson on VLE

6 Current Apply Tasks

Phase III Workbook with tasks 7-30

Completed: 1.Apply task

See above

7 Potential Difference

DO NOW Apply tasks



Session 7 Potential Difference 1 on VLE

8 Potential Difference

DO NOW Apply tasks

Phase III Workbook with tasks

Completed: 1.DO NOW

Session 8 Potential Difference 2 on VLE

3

Pages 37-39

2. Apply tasks

9 Series and parallel

DO NOW Check for Understanding Task


Completed: 1.DO NOW 2.Check for Understanding Task

Session 9 + 10 Series and parallel lesson on VLE

10 Series and parallel

Apply Tasks


Completed: 1.Apply task

See above

Exam question answers

Pages 48-57

4

Session 1

Static Electricity and Atomic Structure

Do Now:

1. Which of the two boxes A and B show an element.

2. How can the particles in box B be separated?

3. What kind of separation system is used when you make tea?

4. Explain why box A shows a solid and why box B shows a gas You must refer to the arrangement of both

Sentence starter: Box A shows a solid because… Box B shows a gas because…

Atomic Structure

All substances are made of atoms. These are often called particles. An atom is electrically neutral - has no overall electrical charge. However, each atom contains even smaller particles called electrons.

• Each electron has a negative charge.

• If an atom gains an electron, it becomes negatively charged.

• If an atom loses an electron, it becomes positively charged.

A B

5

Label the diagram of this atom and complete the table, explaining whether it is positive,

negative or neutral.

Repulsion and Attraction

Two charged objects will:

• repel each other if they have like charges (they are both positive or both negative)

• attract each other if they have opposite charges (one is positive and the other is negative)

-

-

-

+

+

6

Complete the table, drawing the example and stating if it will attract or repel each other

The first column has been done for you

Charges Example Attract or repel

Like

Like

Unlike

8

Session 2

Do Now:

Correct the following statements

1. Electrons are found in the nucleus

2. Protons are negative

3. Neutrons are found in shells

4. Like charges attract

Electrons can move from one substance to another when objects are rubbed together. You may have done this with a party balloon: if you rub a balloon on your sweater, you can get the balloon to stick to the wall or to your hair. This is because of static electricity.

Moving charges

When you rub two different materials against each other, they become electrically charged. This only works for electrically insulated objects and not with materials like metals, which conduct.

Transferring electrons to an object gives it a negative charge

Jumper and balloon example

Electrons transfer from the jumper to the balloon so…

- the balloon is negatively charged up

- The jumper is positively charged up

Q1 What happens when you charge up plastic and place it near a stream of water?

(Watch youtube video in the powerpoint to help you with this question)

Keywords you must use:

Negatively charged

Electrons

Protons

9

Explain what is happening at each step using the diagrams showing the charges to help

you.

1. Before rubbing the hair with the balloon

There are equal positive and negative charges in the hair and balloon so they do not have overall charge.

2. During rubbing the hair with the balloon

The balloon gained …

3. The balloon sticks to the hair

The balloon is [positively/negatively] charged. The hair is ……………….. charged. So …

4. The hair stands on end

Each strand of hair is …

So the strands of hair …

Stretch: Explain why a ruler that is rubbed with a cloth can bend a stream of water.

Keywords: electrons charge repel

- -

- -

+

+ +

-

- +

+

+

Hair Balloon

- -

-

-

+

+

+ - -

+

+

+

- -

-

-

+

+

+

- - +

+

+

+

+

+

+ +

+

10

Correct the following statements

1. Friction causes protons to be transferred

2. When electrons are transferred, it makes an object positively charged

3. A positive and a negative charge repel

(d) Kevin rubs the whole surface of two strips of the same plastic with a cloth. He hangs strip X on a nylon thread. Then he brings strip Y near one end of strip X.

Describe what will happen to strip X and explain your answer. (2 marks)

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Session 3

Circuits

Do Now:

1. Label the letters in the picture

2. How many electrons, protons and neutrons can you see?

3. Complete the table below

4. Explain how static electricity occurs when you rub a balloon on a jumper

(You must use the keywords; transfer and charge)

A circuit is when components (e.g. bulb, battery) are connected using wires so that electricity

can flow through them.

Part of the atom Charge

Electron

Proton

Neutron

-

-

+

+

A

D

C

B

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We use straight lines and right angles to draw circuits.

Circuits are either series or parallel.

Series circuits have only one route for the electricity to flow.

Parallel circuits have more than one possible route for the electricity to flow.

In a parallel circuit there is a branch where there is more than one pathway (or loop)

13

Draw a series circuit with 1 lamp and 1 cell

14

Draw a series circuit with 2 lamps, 1 cell and 1 switch

Why is this circuit currently incomplete?

Draw a complete circuit using the same components

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Session 4

Do Now:

1. What is a circuit

2. Give 3 examples of components

3. Explain the difference between a series and a parallel circuit

Draw 2 circuit diagrams as examples, explain the difference between a complete circuit and an

incomplete circuit.

Guide components: Switch, cell, 2 lamps/ bulbs

Why are switches useful in electrical devices, e.g. a toaster?

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Complete the exam questions on circuits

Answers are on the student VLE in the document,

‘Circuits exam question mark scheme’

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Q1.

(a) Draw a line from each electrical circuit to the correct circuit diagram. Draw only four lines.

electrical circuit circuit diagram

2 marks

(b) In each circuit below, bulb 1 breaks and goes off.

Under each circuit diagram below, tick the correct boxes to show if bulb 2 and

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bulb 3 are on or off.

circuit A circuit B

2 marks

(c) Give the name of the part that provides energy for each circuit.

........................................................ 1 mark

(d) Why is copper used for wires in a circuit? Tick the correct box.

1 mark

maximum 6 marks

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Q2. Ben makes a series circuit using two identical cells, a bulb and a switch to turn the bulb on and off.

(a) Draw a circuit diagram of Ben’s circuit. Use the correct symbols.

The cells have been drawn for you.

3 marks

(b) Which part of the circuit supplies the energy?

...................................................................................................................... 1 mark

(c) Ben adds another identical bulb to the circuit in series. How does the brightness of the first bulb change?

...................................................................................................................... 1 mark

(d) How will the brightness of the bulbs change when the cells shown below are placed into Ben’s circuit?

(i)

............................................. 1 mark

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(ii)

............................................. 1 mark

maximum 7 marks

Q3.

Daniel connected up the following circuit, using a battery, three bulbs and a switch.

(a) The switch is shown in position A. Which bulb is lit up?

......................… 1 mark

(b) Daniel moves the switch from position A to position B.

What, if anything, happens to bulbs J, K and L?

bulb J: ..........................................................................................................

bulb K: ..........................................................................................................

bulb L: ........................................................................................................... 2 marks

(c) Daniel uses a piece of copper wire to connect points P and Q.

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Which of the bulbs, if any, are lit up?

.................................................................. 1 mark

Maximum 4 marks

Q4.

(a) The drawing below shows the parts of a torch.

(i) Paul closed the switch. Why did this turn on the torch?

.............................................................................................................

............................................................................................................. 1 mark

(ii) The diagrams below show symbols for a battery, a bulb and a switch. Connect the symbols to make a series circuit for the torch.

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1 mark

(b) The drawings below show two other torches. In both torches, the bulbs will not light even when Paul closes the switches.

Look carefully at the drawings.

(i) Why is the circuit of torch A not complete?

............................................................................................................. 1 mark

(ii) What could you do to torch B to get the bulb to light?

............................................................................................................. 1 mark

(c) When Paul bought his torch there was a paper strip between the contacts of the switch as shown below.

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Paul had to remove the paper strip before he could turn the torch on. Give the reason for this.

.....................................................................................................................

..................................................................................................................... 1 mark

maximum 5 marks

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Session 5

Do Now –

1. Draw a bulb symbol

2. Draw a battery symbol

3. What component can stop current flowing around a circuit

Stretch: Explain the difference between a series and a parallel circuit, using circuit

diagrams to support your points

Check answers by looking at the powerpoint/video, make notes from the

powerpoint/video and you can use the information below as well. All answers are found

on powerpoint/video

Some particles carry an electric charge (like protons and electrons). When it comes to wires,

these particles are electrons. We get an electric current when these electrons move from place

to place. Current is just a flow of charge, and in wires, this is a flow of electrons. These

electrons come from a battery/cell/power pack and for a current to flow you need a complete

path for the electrons to pass through (also known as an electric circuit).

KEY POINT: Current is a measure of how much electric charge flows through a circuit.

The more charge that flows, the bigger the current.

Current is measured in amperes. The symbol for ampere is A. For example, 20 A is a bigger

current than 5 A. The word ‘ampere’ is often abbreviated to ‘amp’, so people talk about how

many amps flow.

A device called an ammeter is used to measure current. Some types of ammeter have a pointer

on a dial, but most have a digital display. To measure the current flowing through a component

in a circuit, you must connect the ammeter in series with it.

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Complete check for understanding – Remember, answers are on video/powerpoint.

Choose the correct answer

(a) What is current?

1. How the electricity flows around a circuit

2. The amount of charge flowing around a circuit

3. How much power the battery has

(b) What component is used to measure current?

1. Voltmeter

2. Cell

3. Ammeter

(c) What units are current measured in?

1. Electrons

2. Volts

3. Amps

(d) What is the unit for Amps?

1. A in a circle

2. A

3. Ammeter

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Session 6

Do Now

Check answers by looking at ppt/video

Make notes based on powerpoint and below information

You can measure how current changes and the brightness of the bulb changes when more

bulbs are added to a series circuit. The more bulbs that are added to a circuit, the lower

the current will be. The more bulbs that are added to a circuit, each bulb will have a

lower brightness.

The current is the same everywhere in a series circuit. It does not matter where you put the

ammeter, it will give you the same reading.

Current is different at different points in a parallel circuit. Current is shared between

branches in a parallel circuit. The current at each branch should add up to the current

coming from the cell.

Try for yourself – See if you can work out what the readings should be at each Ammeter.

Answers on ppt/video.

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Complete the apply tasks below. Mark using the powerpoint/video.

Extension – Write a method for an investigation to find out the current at different

positions in the same circuit.

Apply tasks -

Q1.

1. What is the name of the equipment used to measure current and what are the units of current?

2. What is the difference between a series and a parallel circuit.

3. How would current change if more bulbs are added to the circuit?

4. How would brightness change if more bulbs are added to the circuit?

5. Suggest how you can increase the brightness of a bulb in a series circuit. 5 marks

Q2.

Peter measured the current through each of three similar bulbs in a parallel circuit.

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He had only one ammeter and he placed it first at A1, then A2, then A3, in order to

measure the currents.

The table shows his results.

position of ammeter current, in amps

A1 0.14

A2 0.16

A3 0.15

(a) He expected the current readings to be the same for each bulb but found they were different.

Hint: In series circuits the current is the same everywhere. Think about a

parallel circuit then.

Suggest two reasons why the readings were different.

1. ................................................................................................................

2. ................................................................................................................

2 marks

(b) Peter then measured the current at A4 and recorded it as 0.45 A. He

concluded

that the current at A4 could be calculated by adding together the currents

through each of the bulbs at positions A1, A2 and A3.

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He added two more similar bulbs to his circuit, in parallel. The current through

each bulb was 0.15 A.

Use Peter's conclusion to predict the current at A4 with the 5 bulbs in the

circuit.

Hint: Current split into 0.15A at the bulbs. When it returned to point A4, what

was the actual current?

................ A

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Session 7

Potential Difference 1

Do Now:

1. 1. If a circuit has no cell, what’s the problem?

2. Draw the symbol for an ammeter

3. Draw a circuit with a cell, lamp and ammeter

What is potential difference (pd)?

Another word for potential difference is voltage/volts/V (named after Italian physicist

Alessandra Volta, who invented the first electric battery).

PD is the force at which electricity moves through a conductor, such a metal wire. The greater

this force, the greater the PD. For example, an AA battery exerts a PD of 1.5 volts while your wall

socket exerts 240 volts. The AA battery will not harm you, but the socket will because more

energy is being transferred into you. If I added batteries together, I can increase the voltage. So

if one AA battery has 1.5V, two AA batteries have 3V. Voltage adds up.

How can we measure Potential Difference?

Attach the ends of the voltmeter terminals to two different points on a circuit. For example, If I

want to measure the PD across a bulb, I must touch the voltmeter pins on either side of the bulb

as follows:

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Q1.

(a) Draw a diagram to show how 1.5 V cells should be connected together to give

a potential difference of 4.5 V.

Use the correct circuit symbol for a cell.

(2)

A student built the circuit shown in the diagram below.

(b) Calculate the total resistance of the circuit in the diagram above.

Use the equation:

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

Total resistance = _______________________ Ω

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(2)

(c) The resistance of P is 3.5 Ω.

Calculate the resistance of Q.

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

Resistance of Q = ______________________ Ω

(1)

(d) The student connects the two resistors in the diagram above in parallel.

What happens to the total resistance of the circuit?

Tick one box.

It decreases

It increases

It does not change

(1)

Give a reason for your answer.

___________________________________________________________

___________________________________________________________

___________________________________________________________

___________________________________________________________

(1)

(Total 7 marks)

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Q2.

Complete each of the following sentences, A, B, C, D and E, by choosing the correct

ending from K, L, M, N or O.

The first one has been done for you.

A The current through a resistor depends ______________________________

B A direct current _________________________________________________

C In a series circuit, the potential difference ____________________________

D An alternating current ____________________________________________

E In a parallel circuit, the potential difference ___________________________

K _____________________________________ across each component is the same.

L __________________________________________ is supplied by a cell or battery.

M _________________________________________ is constantly changing direction.

N ___________________________ of the power supply is shared by the components.

O ______________________________ on the potential difference across the resistor.

(Total 3 marks)

Q3.

(a) The lamps in the circuits drawn below are all identical.

Each of the cells has a potential difference of 1.5 volts.

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(i) What is the potential difference across the 3 cells that are joined in

series?

______________________________________________________________

Potential difference = _________________________ V

(1)

(ii) What will be the reading on the voltmeter labelled V3?

Voltmeter reading V3 = _________________________ V

(1)

(iii) Which voltmeter, V1, V2 or V3, will give the highest reading?

Draw a ring around your answer.

V1 V2 V3

(1)

(b) The diagram below shows a simple circuit.

(i) Calculate the total resistance of the two resistors in the circuit.

_______________________________________________________

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Total resistance = _________________________ Ω

(1)

(ii) Use the equation in the box to calculate the reading on the voltmeter.

potential difference = current × resistance

Show clearly how you work out your answer.

_______________________________________________________

_______________________________________________________

Voltmeter reading = _________________________ V

(2)

(iii) The current through a resistor at constant temperature changes when

the potential difference across the resistor changes.

Which one of the graphs, X, Y or Z, shows how the current changes?

Write your answer, X, Y or Z, in the box.

[7]

37

Session 8

Do Now:

1. Potential Difference can be measured by a……………………..

2. The units of PD are …………………

3. The total voltage of three 9V batteries is…………….

Difference in PD between series and parallel circuits?

PD stays the same even when it branches out into different wires.

However, PD only goes down when it goes through components.

Parallel = voltages all the same

Series = add voltages together

How can we calculate Potential Difference?

Therefore, using this formula triangle, we can make the following equations:

(Tip: cover the letter your seeking the answer for. If I want to know what V is, I cover it and all I

see now is I and R. So the formula will be V = I x R

Voltage (V) = Current (I) x Resistance (R)

Current = Voltage ÷ Resistance

Resistance = Voltage ÷ Current

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1. For the following series circuits calculate the potential differences across the bulbs and the cells. Assume all bulbs are identical.

2. For the following parallel circuits calculate the potential differences across the bulbs and the cells. Assume all bulbs are identical.

1.5V

1.5V

1.5V

1.5V

1.5V

1.5V

4.5V

9V

V

3V

3V

1.5V 1.5V

1.5V

39

Circuit Calculations

1. Calculate the voltage in the following circuits:

a. Current = 2A, resistance = 10 Ohms

b. Current = 5A, resistance = 2 Ohms

c. Current = 100A, resistance = 2.3 Ohms

2. Calculate the current in the following circuits:

a. Voltage = 10V, resistance = 2 Ohms

b. Voltage = 120V, resistance = 40 Ohms

c. Voltage = 230V, resistance = 5 Ohms

3. Calculate the resistance in the following circuits:

a. Voltage = 230V, current = 10A

b. Voltage = 12V, current = 1.5A

c. Voltage = 60V, current = 2A

4. Des uses the following circuit to find the resistance of a lamp:

Brightness of bulb Current Voltage Resistance

bright 3A 12V

dim 2A 6V

(a) Complete the table of results to find the two missing resistances.

(b) How does the brightness change with the voltage through the bulbs?

power

supply

A

V

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Session 9

Do Now – Answers on ppt/video

1. What is potential difference measured in?

2. What do we use to measure potential difference?

3. Potential difference is the difference in/between what?

Stretch: What is wrong with this circuit

In a series circuit, if a lamp breaks or a component is disconnected, the circuit is broken

and all the components stop working. Series circuits are useful if you want a warning that

one of the components in the circuit has failed. They also use less wiring than parallel

circuits.

The current is the same everywhere in a series circuit. It does not matter where you put

the ammeter, it will give you the same reading.

If you put more lamps into a series circuit, the lamps will be dimmer than before because less current will flow through them.

You might think that the current gets less as it flows through one component after another, but it is not like this. The current is not used up by the components in a circuit. This means that the current is the same everywhere in a series circuit, even if it has lots of lamps or other components, as shown below.

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In a parallel circuit, there is more than one loop or branch. In a parallel circuit, if a lamp

breaks or a component is disconnected from one parallel wire, the components on

different branches keep working. Unlike a series circuit, the lamps stay bright if you add

more lamps in parallel. Parallel circuits are useful if you want everything to work, even if

one component has failed. Therefore, our homes (and things like Christmas lights) are

wired up with parallel circuits.

When two components are connected in parallel, the current is shared between the

components. The current is shared when it reaches the branches, then adds again where

the branches meet.

The four rules you must know are that

In a Series circuit :

• Current is the same everywhere

• Potential difference is shared between components

In a Parallel circuit:

• Current is shared between branches

• Potential difference is the same in the cell and the branches.

Check for Understanding – answers on ppt/video

43

Session 10

Do Now – answers on ppt/video

Apply tasks – Current and Potential Difference in Series and Parallel Circuits

Complete the current or potential difference for each circuit. Assume all the bulbs are identical. Make sure to write what rule you used to help work it out.

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Apply task exam questions – Answers on ppt/video

Q1.

46

A pupil makes some electrical circuits. Each circuit contains a motor and a buzzer. The motor and the buzzer can be switched on or off by three switches, A, B and C.

Symbols for an open switch and a closed switch are shown below.

By each circuit diagram, state whether:

the motor is on or off; the buzzer is on or off.

(i)

The motor is ................................

The buzzer is ................................ 1 mark

(ii)

The motor is ................................


(iii)

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The motor is ................................


(iv)

The motor is ................................


(v)

The motor is ................................


Maximum 5 marks

48

Mark schemes – Session 3 + 4

Q1.

(a) •

award two marks for all four correct lines award one mark for any two or three correct lines if more than one line is drawn from any box, do not credit either line

2 (L3)

(b) • off off

both ticks are required for the mark if more than one box is ticked in any row, award no mark

1 (L3)

• on on

both ticks are required for the mark if more than one box is ticked in any row, award no mark

1 (L4)

(c) • battery

accept ‘cell’ or ‘cells’ 1 (L4)

(d) • Copper is a good conductor of electricity.

if more than one box is ticked, award no mark 1 (L3)

[6]

49

Q2.

(a) • correct bulb symbol

accept other symbols for a bulb e.g. 1 (L4)

• correct switch symbol

do not accept a closed switch 1 (L4)

• components connected in series

accept circuits with the components in a different order

accept incorrect but recognisable symbols or drawings for the third marking point only

do not accept responses where the number of components is incorrect

1 (L4)

(b) • cell(s)

accept ‘battery’ 1 (L3)

(c) • the bulb would be dimmer

accept ‘it decreases’

accept ‘it would become dimmer’

‘the current is less’ is insufficient ‘there is less power’ is insufficient a comparative answer is required for the mark ‘it would be dim’ is insufficient as it does not describe the change do not accept ‘it goes out’

1 (L4)

(d) (i) • increase

accept ‘brighter’ or ‘becomes bright’ accept ‘stronger’

‘there is more power’ is insufficient a comparative answer is required for the mark ‘it is bright’ is insufficient as it does not describe the change

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1 (L4)

(ii) • bulbs would go out

accept ‘no brightness’ or ‘no light’ accept ‘it decreases’ accept ‘weaker’

‘not bright’ is insufficient ‘none’ or ‘nothing’ are insufficient ‘there is no power’ is insufficient ‘darker’ is insufficient

1 (L4)

[7]

Q3.

(a) J 1

(b) bulb J goes out or is off

do not accept ‘nothing happens’ 1

both bulb K and bulb L are required for the mark

bulb K lights up or is on

accept ‘bulb K is dim

bulb L lights up or is on

bulb L is dim’ 1

(c) the answer should indicate that all three bulbs are lit

J, K and L or all of them 1

[4]

Q4.

(a) (i) any one from

• it let the current or electricity flow

• current could flow through the bulb

• it completed the circuit

accept ‘the contacts came together’ 1 (L3)

(ii) all three components must be correctly connected in series

51

accept

a mark may be awarded for any correctly connected circuit drawn with straight or curved wires

award a mark for a correct circuit diagram in which the pupil has drawn the symbols instead of connecting the printed symbols

1 (L3)

(b) (i) any one from

• the bulb is broken or blown

• the filament is broken

accept ‘the coil is broken’

the bulb is not connected properly’ is insufficient 1 (L3)

(ii) turn one of the cells around

accept ‘turn a battery round’

accept ‘turn the battery’ accept ‘put the batteries in the right way’

‘turn the batteries round’ is insufficient the mark may be awarded for a description of the fault eg ‘both batteries are the same way up’

1 (L3)

(c) any one from

• it stopped current from flowing

accept ‘to stop the batteries running down’

• paper does not conduct or is an insulator

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• the circuit was broken or incomplete

accept ‘to stop the contacts coming together’

• so that the circuit can be completed 1 (L3)

[5]

53

Mark schemes – Session 7

Q1.

(a) correct circuit symbol

1

3 cells joined in series in correct orientation

e.g.

ignore absence of + symbol

1

(b)

1

R = 7.5 (Ω)

1

an answer of 7.5 (Ω) scores 2 marks

(c) 4.0 (Ω)

allow their answer to part (b) − 3.5

correctly calculated

1

(d) it decreases

1

the current would be higher (for the same p.d.)

reason only scores if correct box is chosen

or

more than one path for charge to flow

allow current for charge

or

total resistance is always less than the smallest individual resistance

54

1

[7]

Q2.

L

N

M

K

all four in the correct order

2 marks for 2 correct

1 mark for 1 correct

[3]

Q3.

(a) (i) 4.5

1

(ii) 2.25 or their (a)(i) ÷ 2 correctly calculated

1

(iii) V2

1

(b) (i) 30

1

(ii) 8

allow 1 mark for correct substitution

ie 0.4 × 20

allow 1 mark for answers of 4 or 12

55

2

(iii) Y

1

56

Mark Schemes – Session 8

Answers:

3. For the following series circuits calculate the potential differences across the bulbs and the cells. Assume all bulbs are identical.

4. For the following parallel circuits calculate the potential differences across the bulbs and the cells. Assume all bulbs are identical.

1.5V

1.5V

1.5V

4.5V

9V

3V

3V

1.5V 1.5V

1.5V

1.5V

1.5V

1.5V

1.5V

0.75V 0.75V 1.5V

1.5V

3V

4.5V

2V

1.5V

1.5V

0.75V 0.75V

0.75V 0.75V 1.5V

0.75V 0.75V

57

Circuit Calculations

5. Calculate the voltage in the following circuits:

d. Current = 2A, resistance = 10 Ohms Answer: 20 V

e. Current = 5A, resistance = 2 Ohms Answer: 10 V

f. Current = 100A, resistance = 2.3 Ohms Answer: 230

V

6. Calculate the current in the following circuits:

a. Voltage = 10V, resistance = 2 Ohms Answer: 5 Amps

b. Voltage = 120V, resistance = 40 Ohms Answer: 3 Amps

c. Voltage = 230V, resistance = 5 Ohms Answer: 46 Amps

7. Calculate the resistance in the following circuits:

a. Voltage = 230V, current = 10A Answer: 23 Ω

b. Voltage = 12V, current = 1.5A Answer: 8 Ω

c. Voltage = 60V, current = 2A Answer: 30 Ω

8. Des uses the following circuit to find the resistance of a lamp:

Brightness of bulb Current Voltage Resistance

bright 3A 12V 4 Ω

dim 2A 6V 3 Ω

(a) Complete the table of results to find the two missing resistances.

(b) How does the brightness change with the voltage through the bulbs?

The lower voltage gives a less bright bulb.

power

supply

A

V

Year 7 Phase 3 - Ark Globe Academy 7 Science Work Pack Pha… · 2. Check for understanding and...

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