AQA Physics: PHYA1 Tuesday 19th May 2015 (AM) and PHYA2 Thursday 04th June 2015 (PM)x

Im almost 100% sure 27 was the correct angle for alpha, using the proper method people saying its 8.1 are getting confused because alpha is the angle of refraction but its a different angle of refraction to the 65 given to you in the question as 65 is the refraction from glass to block and alpha is the angle of refraction from the block to air

Yes. I'm sure no one has pointed out that 8 degrees is impossible, it is going into air, how the hell can it bend more towards the normal, it had to be greater than the angle of incidence (which was 25 I think) because it is going into a less dense medium.
:biggrin:

Reply 3981

Matt Johnson

2

That paper was so hard in my opinion :/

Reply 3982

slj997

7

Original post by liverpool2044

i got 27.4 and 54.4

same!

Reply 3983

JC_Costales

2

Original post by jhjamie

The angle of incidence was 65.

can you pleas explain to me how? i got 27 as the angle cuz the light was going from a material of high to low refractive index :s

Reply 3984

oMatt

10

Original post by QueNNch

α = 8.1
Theta = 35.5
for me. Angle α was (90 - angle of incidence)!!

Yeah I think that's what I got

Reply 3985

QueNNch

3

Original post by particlestudent

Yes. I'm sure no one has pointed out that 8 degrees is impossible, it is going into air, how the hell can it bend more towards the normal, it had to be greater than the angle of incidence (which was 25 I think) because it is going into a less dense medium.
:biggrin:

But alpha WASN'T the angle of refraction! It was 90 - angle and I'm sure it was.

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Reply 3986

-jordan-

5

Original post by particlestudent

Yes. I'm sure no one has pointed out that 8 degrees is impossible, it is going into air, how the hell can it bend more towards the normal, it had to be greater than the angle of incidence (which was 25 I think) because it is going into a less dense medium.
:biggrin:

8 degrees wouldn't bend more towards the normal. Remember the normal is at right angles to the slope.

Reply 3987

mickel_w

9

Im 99% sure

Alpha 8.9
Theta 53/54

I checked both at the end of the exam...
Alpha was between the ray and the surface of the liquid, hence it was 90-(angle of refraction)

Also, whats the general consensus on grade boundaries ?
How many marks for an A???

Reply 3988

Sbarron

3

Original post by Mattematics

I did breaking stress and Young's Modulus.

Other answers I can remember: v/t graph was a Z shape with the two descending gradients parallel. Think I got ~24kg for the mass of aluminium. Something like 54 for angle alpha (pretty sure it's wrong, I worked out the angle of refraction then subtracted it from 90). 0.4 or something for the distance to the screen. 10.1 for one of the ball questions.

I put 10 to 2sig fig because that was the least accurate value used in the question.... (They had used 2sig AND 3sig so I went with 2)

Reply 3989

Ayaz123

3

Grade boundaries predictions?

Reply 3990

Ewanclementson

6

Original post by QueNNch

α = 8.1
Theta = 35.5
for me. Angle α was (90 - angle of incidence)!!

That's exactly what I got

Reply 3991

TripleScience

Original post by particlestudent

Yes. I'm sure no one has pointed out that 8 degrees is impossible, it is going into air, how the hell can it bend more towards the normal, it had to be greater than the angle of incidence (which was 25 I think) because it is going into a less dense medium.
:biggrin:

It is 8 degrees, the angle of refraction was about 81 degrees, however it asking for the angle from the transparent substance to the angle of refraction. Therefore it was 90-81=8.1, around that value.

Reply 3992

Sniperdon227

5

Original post by JC_Costales

I used the graph above that question and did v=u + at to get 0.25 seconds

Then I used s=(u+v)/2 x t , rearrange it and got 40

He must of been andy murray to smash the tennis ball like that

Reply 3993

particlestudent

13

Original post by -jordan-

8 degrees wouldn't bend more towards the normal. Remember the normal is at right angles to the slope.

Yeah so surely because the angle from the normal is smaller, it is bending towards it........

Reply 3994

QueNNch

3

Original post by mickel_w

Im 99% sure

Alpha 8.9
Theta 53/54

I checked both at the end of the exam...
Alpha was between the ray and the surface of the liquid, hence it was 90-(angle of refraction)

Also, whats the general consensus on grade boundaries ?
How many marks for an A???

Original post by Ayaz123

Grade boundaries predictions?

Same or less than last year's.
People did make mistakes because questions were tricky.

Reply 3995

oMatt

10

Original post by Ayaz123

Grade boundaries predictions?

People at my school agreed it was pretty easy so I think lowest for and A might be 78% (near 80% raw)

Reply 3996

particlestudent

13

Original post by TripleScience

It is 8 degrees, the angle of refraction was about 81 degrees, however it asking for the angle from the transparent substance to the angle of refraction. Therefore it was 90-81=8.1, around that value.