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# AQA Physics P3 Unofficial Mark Scheme watch

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1. Hi everyone, I saw a high demand for a mark scheme so I decided to make one. Remember that this is an unofficial mark scheme, yet most of the answers here are correct. I may have included a P2 question, i'm not sure. Or forgot a question or two.

Also these are not in the correct order

Feel free to criticise and utilise.

P3 Unofficial Markscheme

Two labelled points on the eye
The retina and The Suspensory Ligaments

Job of the iris
The iris has muscles, which contract and relax to alter the size of the pupil and controls the amount of light going in

What condition do you call the diagram of the eye?
Short sighted-ness

Feature of liquids that makes the pressure equal
Virtually Incompressible

Hydraulics
300000x0.28
=84000N

Minimum Ultrasound hearing
20,000Hz

The wavelength is the diameter of
An atom

Bus toppling over, why would they test it further?
For strength and support
For extreme cases such as earthquakes and tremors

Rocket Launch
As the angle of projection increased, the range decreased and as the rocket launched closer to a 90 degrees angle it got a higher height.

How many turns on the coil?
18

Units for focal length
Metres, m

What effect does this experiment show?
The Motor Effect

Diagram of the light from the air to the glass prism
Should’ve drawn the light continued along the boundary

What direction would the wire move?
Upwards

Toothbrush. An alternating potential difference in the primary coil causes alternating current in the secondary coil. Explain how
An alternating potential difference/ voltage is induced across the secondary coil. This causes an alternating current / potential difference in the primary coil which creates an alternating magnetic field in the iron core.

Why is the power of the lens important from the muscles?
Because the muscles control the thickness

Bus topple pt.2
The line of action/centre of mass lies outside the base resulting in a clockwise moment

What will the A.C. current do to the movement wire?
The wires will move in both directions due to an alternating magnetic field

What force supplies the centripetal force for the car going round the bend?
Friction

Focal length maximum change
1/0.02 = 50m

Angle of I, and when working out Angle of r
You had to use the inverse sine rule, can’t remember the figures
The answer was 26 degrees

What would happen to the wire in the low frequency alternating current and why?
It would move up and down/ would vibrate due to the magnetic poles/field changing direction

Refractive Index, air to water
1.4 –Rounded

Graph about comparing the 10year old and 30 year old to the 50 year old and the 70 year old
Can’t remember exactly, but to get the marks you would say:
There was a greater decrease between 50-70 it was 3.3 and from 10-30 it was 2.7.

What is the focal length?
P=1/f
P=1/0.8
P= 1.25 dioptres

Two conclusions from the pendulum table
As the length increases, the number of oscillations decreased
The mass of the pendulum has no effect

How can she improve the validity of her readings?
Repeated readings/Repeat more than 3x
Calculate a mean number of oscillations
Acquiring results from other people, making sure it's reproducible

Estimate the power range of a 90 year old
0.4D

Why is the formula one car stable or balanced?/Why doesn't it topple?
It has a low centre of mass
It has a wide base

Factors affecting the centripetal force?
The mass

Which way?
D

6 marker. Compare the medical uses of X-rays and Ultrasound. You must include some advantages and disadvantages in your answer.
X-rays
They are ionising
They knock off electrons from atoms
Increased risk of mutation in cells
Increased risk of cancer to mother and/or baby
Can cause abnormal cell growth
Used to identify bone fractures and teeth
Can be connected to a CCD to produced a digital image
Lower dose of x-ray radiation
Only produces a 2D image
Cheaper

Ultarsound
Non ionizing
Less risk of cancer
Produce a clearer image of soft tissues
Can be used in prenatal scanning, to check whether the foetus inside a mother’s womb is healthy
Can be used to break down kidney stones in the body then pass out the body as normal

ORDER

Pendulum

Focal length (2 marks)
p = 1/f
p = 1/0.8
p = 1.25 dioptres

Two conclusions can be made from the table? (2 marks)

-As length of wire increases, number of oscillations decrease
-As mass increases, there's no change to oscillations.

How can she improve the validity of her conclusions (2 marks)
-Repeated readings, calculating a mean.
-Acquiring results from other people, making results reproducible.

Units for formal length (1 mark)Metres, or M.

Eye

Labeling (2 marks)

-Suspensory ligaments
-Retina

Function of iris (1 mark)

Muscle contracts or relaxes, controlling amount of light entering pupil.

Defect&how to correct (2 marks)

Short sighted and diverging lens.

Diverging graph (3 marks)

Why is it important for the power of the lens be adjusted? (1 mark)

They allow the eye to focus on objects both far away and close, ie changing the power of the lens.

Power graphFrom the age 10-30 and 50-70, what happens to power of lens? (3 marks)

There was a greater decrease between 50-70 it was 3.3 and from 10-30 it was 2.7.

Estimation of a 90 year old woman (1 mark)

0.8 Dioptres

Ultrasound and x-rays

Two missing blanks (2 marks)

-20 000 minimum frequency
-Diameter of an atom.

6 mark question on comparative reasons, uses, risks and precautions.

X-rays

-Used in x-rays and CT Scanner
-Absorbed by bone to check for fractures.
-Are ionising so harmful to cells/tissues and could cause cancer. Hence why the person conducting would stand behind a screen.

Ultrasound

-Ultrasound is used for prenatal scanning and to break up kidney stones.
-Ultrasound is just a sound wave and has no risks compared to X-rays-which are ionising.
-Has a frequency higher than 20,000 hz.

Centripetal force and CM.

Which way? (1 mark)

D.

Force? (1 mark)

Friction.

Factors affecting? (2 marks)
-Mass

Why is it hard for race car to topple over? (2 marks)
-Height of the car is small, therefore low cm and harder to topple over.
-Base of the car is large, so more stable.

Bus questionWhy does the bus topple over once it reaches a certain angle? (2 mark)

Topples over because the line of action from the cm is beyond the base.

Give two reasons why they test angles that wouldn't normally happen at normal occurrence (2 marks)

-The greater the angle the bus can stand the more stable it is.
-Testing all circumstances such as an event of a tornado or earthquake.

Motor effect

Why does the wire move when the switch is turned on? (3 marks)

Permanent magnets would produce a magnetic field and when the switch closed that'll produce a magnetic field because current would be running through the wire, both interfere with each other exerting a force.

Direction of force? (1)

Downwards.

When a.c is used what's the motion of the wire? (2 marks)

Moves both directions, because a.c would produce an alternating magnetic field.

What's the effect called? (1 mark)Motor.

Hydraulics

Property for liquids (1 mark)
-Water is virtually incompressible.
Accept "Water can equally transmitted through the water?"

Working out force hydraulics (3 marks)
-Mark for rearranging equation, making force subject.
-Mark for applying knowledge that pressure is the same throughout the water, so knowing this you'd work out pressure from first piston.

Refraction, critical angle.

Finish the line for refraction in figure x (1 mark)

Moves away from normal, because it's coming from high density to low density so speeds up.

Critical angle (2 marks)

-Mark for correct use of equation Refractive index = 1/ sin c
=1.56

Transformers

How is voltage created in the secondary coil? (3 marks)

An alternating current in the primary coil produces a changing magnetic field in the iron core and hence in the secondary coil. This induces an alternating p.d across the ends of the secondary coil.

How many turns in secondary coil?(2 marks)

-Mark for correct equation.
-18 turns for answer.
2. Angle of I, and when working out Angle of r
You had to use the inverse sine rule, can’t remember the figures
angle r was 26 degrees *

Two conclusions from the pendulum table
As the length increases, the number of oscilations decrease *
The mass of the pendulum has no effect
3. angle of r was 26 degrees
4. (Original post by Jimmy Singh)
Angle of I, and when working out Angle of r
You had to use the inverse sine rule, can’t remember the figures
angle r was 26 degrees *

Two conclusions from the pendulum table
As the length increases, the number of oscilations decrease *
The mass of the pendulum has no effect
The conclusions was a typo, cheers man
5. There was also a question about using the graph to estimate the power range of a 90 year old but I can't remember the answer
6. (Original post by Jimmy Singh)
There was also a question about using the graph to estimate the power range of a 90 year old but I can't remember the answer
Oh yeahh, I think I put 1.4 or 0.4 I can't remember
7. Another question: Why is the formula one car stable or balanced (not sure of the exact question) (2 marks)
Answers: It has a low centre of mass
It has a wide base
8. oh yh I put 0.45 but I think the examiner should give you the mark if your answer was between 0.4/0.5
9. (Original post by Jimmy Singh)
oh yh I put 0.45 but I think the examiner should give you the mark if your answer was between 0.4/0.5
Yeah the question about the defect of the lens, what did you put?
10. Not sure sorry, what was the question?
11. (Original post by Jimmy Singh)
Not sure sorry, what was the question?
Not sure either don't worry, I got short sightedness idk
12. Oh that question yh you are right it was short sightedness, it had a diagram showing two lines crossing which is due to short sightedness
13. I'm certain the movement was up, my physics teacher told us today it was up also

Posted from TSR Mobile
14. I can't remember the paper that well but im sure the short sight one...it was long sight? as the eyeball was too short this makes it long sight? I have glasses and that condition so thats how i learnt it.
15. how many marks was the question about how the validity of the readings could be improved
16. (Original post by amymcavoy22)
I'm certain the movement was up, my physics teacher told us today it was up also

Posted from TSR Mobile
Okay thanks
17. (Original post by amymcavoy22)
I'm certain the movement was up, my physics teacher told us today it was up also

Posted from TSR Mobile
I also put up i used that hand thing I don't know im confused lol
18. (Original post by Jimmy Singh)
how many marks was the question about how the validity of the readings could be improved
It was 2 marks, but I gave 3 reasons as 1 of them could be in the 'accept' or 'allow' section of the mark scheme
19. two
20. could you say to use smaller intervals for the lengths as it would help to make the results look more accurate?

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