Question

Red light with a wavelength of 7.0x10^-7 m travels at a speed of c. When it enters glass it's speed is reduced to 2.0x10^8 m/s. Calculate the wavelength of this redlight in glass. Assume that the frequency does not change.

I'm really confused and I'm not sure how to do this question. Thank you!

Answer 1

Ohh wait never mind.
Would it be
TIME = 7.0x10^-7 m / 2.0x10^8 m/s
=35s

And then you would plug it in as f=1/35s?

Answer 2

watch the units

wavelength(m) = speed(m/s) / frequency(1/s)

Answer 3

I don't understand. So is the 35s part not right?

Because then you could plug it into the f=1/t formula.

Answer 4

It should be 0.35 seconds, shouldn't it?

Answer 5

Oh wait I see, so then do you use the v=fx so solve for the frequency?

Like
2.0x10^8 m/s = 7.0x10^-7 m f

And then use that frequency to find the new wavelength?