Modern lasers can create a pulse of light that lasts only a few femtoseconds.

Question

Modern lasers can create a pulse of light that lasts only a few femtoseconds.

(a) What is the length of a pulse of blue light that lasts 5.8 fs?

______________m

(b) How many wavelengths of blue light (λ = 480 nm) are included in such a pulse?

_____________wavelengths

Answer 1

Convert 5.8 fs to seconds, and divide the speed of light in m/s by that answer to get the length of the pulse.

Convert 480 nm to meters, and divide the length of the pulse by that answer to get the wavelengths.

Answer 2

a) Length of pulse = time duration of pulse x speed of light

b) Divide your answer from (a) by 480 x 10^-9 m

Make sure you understand why this works.  Over to you.