Index of refraction and speed of light.

[jakey]

Oh btw, this is not a homework question! just got it somewhere.
Light travels in a medium of n=1.2 at c1. what is its speed in a medium of n=1.6?

a)1.3c1
b)0.67c1
c)2c1
d)1.7c1
e)0.55c1

my solution:
using n=c/v, 1.2 = c/c1. also, 1.6=c/c2. c2= c/1.6. but c=1.2c1

So, c2=(1.2/1.6) c1=0.75c1. but it isn't in the choices. any help? thanks

also, do you know where i can find review materials for a-level physics (this is like UK based)? I am preparing for university entrance exams. thanks!:>

 

[CompuChip]

Your reasoning is correct, the answer should be 0.75 c1.
Are you sure you copied all the numbers correctly?

 

[jakey]

Your reasoning is correct, the answer should be 0.75 c1.
Are you sure you copied all the numbers correctly?

i'm so sure that's why I'm so confused. however, 1.6/1.2=1.3 and its in the choices.

 

[CompuChip]

That's why I asked you to check the question.. if you'd interchange the 1.2 and 1.6, then the answer is there.