GENERAL PHYSICS LAB MANUAL Imam Mohammed bin Saud University Science Collage 1 Physics Lab Science...

GENERAL PHYSICSLAB MANUAL

Imam Mohammed bin Saud University

Science Collage

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Physics Lab Science Collage-Imam University

Physics 101Lab


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General physics course is mainly about mechanics and electricity. You will perform basic physics experiments.

Hope you enjoy your physics lab ….

Lab Rules

All students must attend the lab section. No food. No drinks. The lab must be clean at all time. Ask your teacher to check all electrical circuits

before turning on the power supply. Before making any adjustments on your

electrical circuit make sure it is turned off. At the end of each lab switch off and unplug any

electrical equipment and disconnect all circuits and arrange all equipment tidily on the bench.

Lab reports must be submitted in a week’s time. Lab reports writing must be an individual effort

although the experiments will be performed in groups.

The lab is worth 20% of the course’s grade. A missed lab will receive a zero grade. A make up lab must be performed during the

same week of the missed lab if your instructor accepts your excuse.

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Lab reportguide


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Your lab report should consist of:

Title Page: The following information must appear all by itself on the first page:

– the title of the experiment– your name– the names of your partners, if any– the performance date– the course and section numbers– the name of your Lab Instructor

Introduction:– Objective, method and results.

Experimental procedure:– Description of apparatus and outline of technique.

Discussion: Here you present your data, explain how you reduced your data to a value for the OBJECTIVE, and reflect on the reliability of your result.Data summary: Present the collected raw data here, in tabular form. Any graphs you created should be included in this section, also. Graphs should be drawn on special graphing paper with appropriate scaling. Graphs, tables and figures must have legible titles and captions.

Lab reportguide


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Analysis: Describe, in one paragraph, the mathematical steps used to convert the raw data into the final value reported for the objective.Errors: In a single paragraph comment on the accuracy and precision of the apparatus and include a discussion of the experimental errors and an estimate of the error in your final result. The two principal sources or error are:

– Physical phenomena similar to the phenomena being measured that affect the measured quantity (e.g., stray magnetic or electric fields, unaccounted for friction).

– Limitations of the observer, the analysis and/or the instruments.Conclusion: Restate your results, including the uncertainty in any numerical results. Compare your result with the accepted value. Appendices: Include here the answers to questions assigned from the lab manual. They should be answered in complete sentences using appropriate scientific terminology.

Experiment 1Balancing force (force table)

Objective:Using the force table to experimentally find the balancing force of two forces.

Theory:Forces are vector quantities which have both magnitudes and directions.

An object with different forces acting on it is considered in equilibrium when the vector sum of all individual forces acting on it is zero, or in other words when the resultant force acting on the object is equal to zero.

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0F

0xF 0yF

Experiment 1Continued

An object moving as a result of different forces can be balanced by an equilibrant force which is equal and opposite of the resultant force of all forces acting on it.

Where FR is the resultant force and FE is the equilibrant force.

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ER FF


There are two methods to fond the resultant force of two forces graphically:

1- Tip to Tail Method:We can add any two forces, F1 and F2, by placing the tail of F2 so that it meets the tip of F1. The sum, F1 + F2, is the vector from the tail of F1 to the tip of F2.

Note that you’ll get the same vector if you place the tip of F2 against the tail of F1. In other words, F1 + F2 and F2 + F1 are equivalent.

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F1 F2

FR


2- Parallelogram Method:To add F1 and F2 using the parallelogram method, place the tail of F2 so that it meets the tail of F1. Take these two forces to be the first two adjacent sides of a parallelogram, and draw in the remaining two sides. The vector sum, F1 + F2, extends from the tails of F1 and F2 across the diagonal to the opposite corner of the parallelogram.

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F1

F2

FR



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Equipment:Force table – stand base – pulleys – hangers – weights (slotted masses) – strings – center ring – protractor .


The force table is a circular table that has the angles 0 degrees to 360 degrees inscribed on the edge.

Pulleys are placed at different angles with strings attached to a center ring running over the pulleys. Masses are placed on mass hangers attached to the end of the strings to provide the forces needed.

By adding the vectors (applied forces), the resultant vector is found. To balance the force table, a force that is equal in magnitude and opposite in direction must counterbalance the resultant. This force is the equilibrant force.

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Procedure:1- Your lab instructor will provide you with two different forces (magnitude and direction). Attach suitable slotted masses with the thin strings to the center ring of the force table. Remember that:F1=M1g and F2=M2gwhere g=9.8 m/s2 which is the gravitational acceleration.2- Consider the direction of each force which is represented by the angle. The force table’s edge will help you identify the angle accurately.3- In order to balance the ring; a third force should be attached.

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4- Record the magnitude and direction of the equilibrium force.5- Plot both original forces on graphing paper by setting a drawing scale (1 cm = 1 N). 6- Find the resultant force graphically. The magnitude of the force is represented by the length of the vector and should be converted using the scale you have chosen. The direction is represented by the angle which you can measure using the protractor.7- Now find the equilibrant force which is equal and opposite to the resultant force.8- Record all values in the following table.9- Find the percentage error.

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Data:

Percentage Error:

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Force 1

Force 2Balancing forcePercentag

e error

graphicallyexperimentall

y

Magnitude

Angle

100Re

Rex

alValue

alValueExperimentalValuePE

Experiment 2Acceleration of Linear uniform

motion

Objective:To calculate the acceleration of an object moving in a straight line with a constant acceleration using equations of motion.

Theory:Equations of motion are used to study the linear motion of a uniformly accelerated body.

where:

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d:Displacement or change in position

vo:Original velocity, the velocity at the start of the acceleration

vf:Final velocity, the velocity at the end of the acceleration.

a:Acceleration, this is a constant acceleration

t:Time, this is the time period of the acceleration.

2advv

atvv

at2

1tvd

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2f

0f

20



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Equipment: Track – trolley – holding magnet – electronic stop clock – light barrier – pulley – mass hanger – slotted weights – cables.


Procedure:1- Set the equipment, use the cable to connect the trolley

with the pulley and the hanging mass.

2- You can perform this experiment by using either one or two light barriers.

3- If you are using a holding magnet and one light barrier. Connect the holding magnet to the stop clock and adjust the voltage so that the trolley is held.

4- Put the light barrier at a certain distance.

5- Release the trolley by stopping the magnet and record the time the trolley took to pass the light barrier.

6- Repeat and record the time three times then calculate the average time and the final velocity.

7- Change the distance and repeat the previous steps for each distance.

8- If you are using two light barriers, place each barrier at certain distance and hold the cart at the first barrier then release it and record the time.

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9- Repeat and record the time three times then calculate the average time and the final velocity.

10- Change the distance and repeat the previous steps for each distance.

11- Whether you used one or two light barriers, tabulate your data.

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Distancem

Time 1s

Time 2s

Time 3s

Average Time

s

Time square

s2


12- Plot a graph between the square time (x-axis) and the distance (y-axis).

13- Draw the best line and find its slope at each graph.

14- Calculate the acceleration from each slope using equations of motion.

15- Find the real value of the carts acceleration using Newton’s second law which states that the force is proportional to the acceleration. F=ma where F could be found from the mass causing the motion of the cart.

16- Find the percentage error of the acceleration.

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100Re

Rex

alValue


Experiment 3Free fall

Objective:To calculate the gravitational acceleration of free falling ball.

Theory:Under free fall all objects have the same constant acceleration, which in metric system is equal to 9.8 m/s2 at sea level. Equations that describe free fall are:

where:

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Δy 2gvv

gtvv

gt2

1tvΔy

20

2f

0f

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Δy:Vertical displacement

vo:Original velocity, the velocity at the start of the acceleration

vf:Final velocity, the velocity at the end of the acceleration.

g:Acceleration due to gravity

t:Time, this is the time period of the acceleration.



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Equipment:Steel ball – contact plate – holding magnet – holding magnet adapter with a release mechanism – electronic stop clock – stand base – rods – scale – connecting leads.


Procedure:1- Set the equipment and hold the steel ball

using the holding magnet at a certain height.2- Release the ball and read the time the ball

took traveling the vertical distance, then reset the stop clock and reattach the ball and read the time again , you should take three readings of the time then find the average time the ball has traveled.

3- Reduce the height and repeat the previous steps.

4- Tabulate your data.

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Height

m

Time 1

s

Time 2

s

Time 3

s

Average Time

s

Time square

s2


5- Plot a graph between the square time (x-axis) and the height (y-axis) or displacement of ball.

6- Draw the best line and find its slope.7- Calculate the gravitational acceleration from

the slope using equations of free fall.8- Find the percentage error.

9- Repeat the previous steps using a different mass ball.

10- State your observation

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100Re

Rex

alValue


Experiment 4Conservation of mechanical

energy

Objective: To find the final velocity of an object sliding an incline with constant acceleration using energy conservation law.

Theory:Energy is the ability to do work and is measured by Jouls. Mechanical energy has two different forms:Potential energy is the energy an object stores due to its position.The gravitational potential energy is given by:

PE = m g hWhere m is the mass of the object, g is the gravitational acceleration and h is the height of the object.Kinetic energy is the energy of motion.The kinetic energy is given by:

KE = (1/2) m v2

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The total mechanical energy E, of any isolated system of objects, is defined as the sum of the kinetic and potential energies:

E = PE + KEThe principle of conservation of energy could be written as:

Ei = EfWhere Ei is the initial energy and Ef is the final energyAn object on an incline will move down with constant acceleration. Energy conservation law: Ei = Ef

KEi + PEi = KEf + PEf

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(1/2) m vi2 + m g hi = (1/2) m vf2 + m g hf If the object starts from rest, we get:

m g hi = (1/2) m vf2 + m g hf(1/2) m vf2 = m g hi – m g hf

(1/2) vf2 = g hi – g hf

From the equations of motion:d = (1/2) (vi + vf) t

If the object starts at rest, we get:vf = 2d / t

Which means that the final velocity could be found either by the energy conservation law or by equation of motion.

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)h2g(hv fif



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Equipment:Track – trolley – holding magnet – electronic stop clock – light barrier – cables.


Procedure:1- Set the track so that it will become an incline by rising one side of it, use the holding magnet to hold the trolley still.

2- Connect the stop clock with a light barrier and put the light barrier at a certain distance and record the distance that the trolley should travel.

3- Measure the height at the beginning and at the end of the motion of the trolley.

4- Release the trolley and find the time it needs to travel the distance three times and find the average time of traveling.

5- Use the equations to find the final velocity. The two values should be equal.

6- Find the percentage error.

7- Calculate the initial and final PE and KE.

8- Repeat the previous steps by changing the height, the mass and the distance and conclude their effect on energy.

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Experiment 5Ohm’s Law

Objective:– To test Ohm’s law by plotting V versus I to

determine the value of a resistor.– To calculate the equivalent resistance of

two resistors in series.– To calculate the equivalent resistance of

two resistors in paralle.

Theory:When a constant potential difference, ΔV, is applied to a conducting material, a current density, J, is established that is directly proportional to the electric field, E, created within the material. The constant of proportionality is known as the electrical conductivity, σ and the relation is known as Ohm's Law:

J= σ E

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The electric field created by the potential difference, establishes a current, I, in the conductor which is directly proportional to the potential difference. By considering the resistance of a given length of material, a more useful and familiar form of Ohm's Law may be derived:

ΔV=IRwhere the constant of proportionality, R, is the resistance of the conductor. where the unit of resistance, ohm.

Some materials resist current very little while others resist current almost completely. In general, the resistance of a material depends on the applied voltage.

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In an electrical circuit, a combination of resistors can be connected as in parallel or in series. The equivalent resistance, R, for the resistors in series is given by

R=R1+R2

The equivalent resistance, R, for the resistors in parallel is given by

1/R = (1/R1)+(1/R2)

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R1 R2

R1

R2


The following chart summarizes the relation between different variables related to Ohm’s law.

Equipment: DC power supply – Ammeter – Voltmeter – breadboard - resistors – connecting leads.

Instead of using ammeters and voltmeters; digital or analogو multimeters could be used.

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Procedure: Part A:– Connect the circuit as in the following figure:

– For each resistance write first the real value then change the voltage V and read the current I, then insert all data in a separate table for each resistance.

– Make sure not to exceed the maximum limit of voltage for each resistance, you can calculate the maximum voltage (use the chart).

– Plot a graph for each resistance between V (x-axis) and I (y-axes).

– Find the slope of each graph.– The value of the resistance R=1/slope.– Find the percentage error for each resistance.

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Part B:– Connect the circuit as in part A; but instead of

using one resistance, use two resistors in series.

– Repeat the procedure in part A to find the value of the resistance.

– Calculate the equivalent resistance of the two resistors in series.

– Find the percentage error.

Part C:– Connect the circuit as in part A; but instead of

using one resistance, use two resistors in parallel.

– Repeat the procedure in part B, but use the resistors in parallel.

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Hints and Cautions:

– All electrical circuits should be handled carefully! – To protect the ammeter (or any voltage or current meter), use

the large scale first and then gradually move to a more sensitive scale. Starting with the sensitive scale first may seriously damage the unit.

– Caution!!! Always monitor the current into the ammeter and do not allow the current to exceed the ammeter's scale!

– In this lab, use only the power supply's dc voltage outputs, not the ac voltage outputs!

– The power supply needs to be set to constant voltage mode. – You should not use the voltmeter and ammeter displays on the

power supply to record the circuit voltages and currents. Instead, use the voltage probe from the analog multimeter.

– The ammeter should always be connected in series with the circuit elements.

– The voltmeter should always be connected parallel to the circuit elements.

– Take your time and carefully plan out how you will solve each Objective.

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Experiment 6Kirchhoff’s Rules

Objective:– To investigate kirchhoff’s rules using resistors

in DC circuits connected in series and parallel.

Theory:When analyzing complicated DC circuits, it is helpful to use two easily stated principles known as Kirchhoff's rules:

Kirchhoff's Current Law: This fundamental law results from the conservation of charge. It applies to a junction or node in a circuit. A point in the circuit where charge has several possible paths to travel. In the following figure , we see that IA is the only current flowing into the node. However, there are three paths for current to leave the node, and these current are represented by IB, IC, and ID.

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Once charge has entered into the node, it has no place to go except to leave (this is known as conservation of charge). The total charge flowing into a node must be the same as the the total charge flowing out of the node. So,

IB + IC + ID = IABringing everything to the left side of the above equation, we get

(IB + IC + ID) - IA = 0∑I=0

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Kirchhoff's Voltage Law: Kirchhoff's Voltage Law (or Kirchhoff's Loop Rule) is a result of the electrostatic field being conservative. It states that the total voltage around a closed loop must be zero. If this were not the case, then when we travel around a closed loop, the voltages would be indefinite. So

∑V=0

In the following figure the total voltage around loop 1 should sum to zero, as does the total voltage in loop2. Furthermore, the loop which consists of the outer part of the circuit (the path ABCD) should also sum to zero.

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Resistors in series: The current passing through the resistors in series is equal but the voltage is devided between the resistors.

Resistors in parallel: The voltage passing through the resistors in parallel is equal but the current is devided between the resistors.

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I0=I1=I2=I3

ΔV0= Δ V1+ΔV2+ΔV3

I0=I1+I2+I3

ΔV0= Δ V1=ΔV2=ΔV3


Equipment: DC power supply – 4 digital multimeters – breadboard - resistors – connecting leads.

Procedure: Connect the circuit with the resistors in series as in the following figure. Measure the current and voltage across each element and show that kirchhoff’s voltage and current rules apply.

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Connect the circuit with the resistors in parallel as in the following figure. Measure the current and voltage across each element and show that kirchhoff’s voltage and current rules apply.

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GENERAL PHYSICS LAB MANUAL Imam Mohammed bin Saud University Science Collage 1 Physics Lab Science...

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