# hsc physics mc answers (1 Viewer)

#### dr

##### New Member
I have worked through the multiple choice questions (being a physics teacher myself) and these are the answers.

1. b ( downward acceleration due to gravity the whole time )
2. a
3. b
4. b
5. d (using r^3/t^2 ratio)
6. a
7. a
8. c
9. c
10. a (emf = change in the rate of flux passing through the area of the coil)
11. a
12. c
13. c
14. b ( silicon is more abundant than germanium - so 'c' cannot be the answer )
15. a #### spice girl

##### magic mirror
Originally posted by dr

10. a (emf = change in the rate of flux passing through the area of the coil)
Dear Sir/Miss,

You might like to rethink Q10.

emf is the rate of change of flux blablabla. Because the coil rotates in a constantly circular nature, the flux in the area of the coil varies sinusodially with time {something like flux = k*sin(at + b)}. As we all know, a sine curve is steepest at flux=0, and horizontal or stationary at max/min flux.

And we also know the rate of change of flux (i.e. d(flux)/dt) is basically the gradient of the curve at any specific point (t,flux).

Thus we have max magnitude emf at P, R, T, and zero magnitude at Q, S.

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#### dr

##### New Member Thanks for that - the answer is 'b' - it was actually a clumsy mistype ( apologies )