Yousuf Wasil Khan

yousufwasil@gmail.com
0344-8920839
Whatsapp: 03448920839 1 By: yousufwasil@gmail.com Yousuf Wasil Khan
1 P3 - 29 April 2023
 P3 Practical Keypoints
Question 1
(Graph based)

Question 2
(Uncertainty based)

Whatsapp: 03448920839 By: yousufwasil@gmail.com Yousuf Wasil Khan

2 P3 - 29 April 2023
Question 1
Steps
1. Read the instructions before
assembling the apparatus to understand
the input (independent variable) and
output (dependent variable) of the
experiment

2. Identify the labelling from diagram

and assemble the apparatus

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3 P3 - 29 April 2023
Question 1

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4 P3 - 29 April 2023
Question 1 1 d.p in cm
8.0 cm
3. Initially Q.1 part (a) the question will
75.5 cm
ask you to record a specific quantity
12 cm Unacceptable
While recording data:
12.00 cm Unacceptable
Make sure the decimal places of
0 d.p in mm
recorded data should match the
decimal places of least count of 80 mm
instrument 12 mm
1) meter rule: 12.0 mm Unacceptable
12.00 mm Unacceptable

3 d.p in m
0.345 m
0.80 m Unacceptable

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5 P3 - 29 April 2023
Question 1 2 d.p in mm only
2) micrometer screw gauge 2.63 mm

2.6 mm Unacceptable

Commonly they ask you to find diameter of

thin wire in which main scale is usually zero
Answers are usually 0.16 mm etc
Tip:
Do not exert pressure on wire
Main scale: Check for zero error
i.e enclose the micrometer screw gauge and check
2.5 mm
whether the zero matches or not

Thimble scale: If there are any extra divisions subtract or add

it from the final reading
13 x 0.01 mm

Final

=2.5 + 0.13
=2.63 mm
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6 P3 - 29 April 2023
Question 1 Usually they ask to find time
period of oscillations
3) Stop watch

Make sure you record for a minimum a time

for 5 oscillations but preferable is 10

Divided the recorded value by 10 to find time

period, T

For individual part make sure to repeat the

experiment for T and find average

1 complete oscillation:

Tip
There is no need
to record first
2 d.p in seconds only oscillation
displace the object
1.89 s 12.0 s Unacceptable and start counting
and stop watch
0.54 s after one or two
7
oscillations
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7 P3 - 29 April 2023
Question 1 5) Newton meter
4) protractor

no d.p in protractor
75° 1 d.p with multiple of 0.2

4.0 N
40.0° Unacceptable
6.8 N
9.7 N Unacceptable

Yousuf Wasil Whatsapp 03448920839 yousufwasil@gmail.com 8 9.80 N Unacceptable

8 P3 - 29 April 2023
Question 1
6) Vernier caliper 7) multimeter

Main scale =
12 mm

Vernier scale
= 0.65 mm

d.p as per display

The multimeter setting is to be set by lab in-

charge. Do not set it yourself
2 d.p in mm with multiple of 0.05
However common ones are 20 V in DCV
e.g 12.65 mm and 200 mA in DCA
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9 P3 - 29 April 2023
Question 1
8) Thermometer

Zero d.p in °C

12 °C 13 .0 °C Unacceptable

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10 P3 - 29 April 2023
Question 1

The question will help you with at least one

reading before they ask you draw table for six
readings

For single part if there are two marks make

sure you show working for average

Make sure you write unit in such blank line

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11 P3 - 29 April 2023
Question 1
For the table part they will mention which Important points for table
columns are required
1) Make column headings/units for each direct
measurement and calculation

e.g d/cm T/s 1/T/s-1 h-h1/cm

Vary h1 means this is the input
2) For direct measurement make sure decimal
For the input try to have maximum possible places are same and consistent with least count
range
See what is the smallest and highest value of h1
possible in the apparatus

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12 P3 - 29 April 2023
Question 1 Graph:

3) for processed value make sure significant

figures are same of the measured value

1) Axis should be labelled

Exactly like column heading

2) False origin can be considered

3) more than 50% of axis should be covered

4) In order to draw line of best fit make sure

to cover equal number of points which is very
rare
Try to have equal number of points above and
below the line
5) For gradient, the points should be on line
4) There should be an overall trend in the
not from table
input and output values
Triangle should be visible which is to cover
more than 50% of line

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13 P3 - 29 April 2023
Question 1

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14 P3 - 29 April 2023
Question 1
Last part
Given equation to be adjusted with y = mx + c

Units of gradient = Y axis units

_________
X - axis units

Units of y - intercept = Y axis units

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15 P3 - 29 April 2023
Question 2
For multiple readings and average

e.g Estimate the percentage uncertainty in your

value of T

(From previous part)

T1 = 1.24 s
T2 = 1.49 s

T3 = 1.18 s

For simple lengths or angles it is usually twice Tavg = 1.30 s

the least count divided by measured value x
100 Formula :

%T = Half the range x

_____________ 100
%L = 2 x least count x 100
_____________ Average value
Measured value
= (1.49 -1.18)/2
______________ x 100

1.30

= 11.9%
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16 P3 - 29 April 2023
Question 2

You have two sets of reading so find two sets

of constants usually denoted by k or c etc

Justification part:
Since the least significant figure in the
measured value of H, y ( or any other named
physical quantity ) is 3 so the value of c should
also be 3 significant figures

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17 P3 - 29 April 2023
Question 2

If value is less than 15% write

Since the percentage variation is less than 15%

the suggested relationship is supported

Otherwise not supported

Find percentage variation in the constant

Kavg = K__________
max + Kmin

%K = K max -
___________K min
x 100
Kavg

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18 P3 - 29 April 2023
 Errors and improvements
Question 2
1. Two readings are not enough to make a valid
conclusion 5. Difficult to release (something) without
Take more readings and plot a graph applying a force
-Use a mechanical hand to release the (thing)
2. The value of (a physical quantity) is small so the like electromagnet
percentage uncertainty of (the quantity) is large
(The way to make the value of the quantity larger) 6. Difficult to shape the plasticine into the shape
of (something)
3. The movement/oscillation of (something) is - Use a mould to shape the plasticine
affected by wind movement
Use a wind shield when carrying out the 7. Heat loss through the sides and bottom of
experiment ( only for lighter objects) beaker/container
-Use polystyrene container or insulate the
4. Difficult to determine the start and end of beaker/container using a lid or lagging.
oscillation/movement of (something) because it
moves too fast 8. The (measuring instrument) is not precise
- Use a video camera with slow motion feature enough
and timer to record the experiment with scale, - Use another (instrument) with greater
then view the video playback frame by frame. sensitivity and precision. You must state the
precision of the suggested instrument.
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19 P3 - 29 April 2023
 Errors and improvements
Question 2
9. The length/diameter/thickness of 14. Friction at pulley
(something) is not uniform Apply oil to lubricate the pulley
Measure the length around/along the (thing)
and calculate the mean 15. Difficult to determine when (something)
reach the maximum height because it remains
10. Difficult to measure (something) due to there for too short a time
(specific reason based on experiment)
(Suggest a better way to measure it) Difficult to take the reading of newton-meter
immediately when (something) starts to move
11. Parallax error when measuring (something) because it moves suddenly
(Suggest a better way to measure it, such as use
mirror scale) Difficult to start or stop the stopwatch
immediately when (something) passes through
12. (Something) moves (somewhere)
(Way to keep it in the original position like
wooden block/ adhesive) Use a video camera with slow motion feature
and (the measuring device) to video the
13. Difficult to maintain (something) at (a experiment with scale, then view the video
particular position) / maintain ruler vertical playback frame by frame..
- Use a clamp
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20 P3 - 29 April 2023
 Errors and improvements
Question 2
9) Resistance / current fluctuating
- Clean contacts with sand paper
- use power supply rather than a cell

10) Wires not straight in electricity practical

-Method of keeping wire (during experiment)
straight e.g. tape to ruler, hang weights off end,
clamp wire.

11) Labelled values of mass may not be accurate.

Improvement:
Use balance/method of weighing mass.

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21 P3 - 29 April 2023