A beam of light has a wavelength of 4.5 x 10−7 meter in a vacuum. The frequency of this light is ___? (Speed of light is 3 X 108 m/s)

1 Answer
Mar 9, 2018

6.67 * 10^14 Hz

Explanation:

wave equation:

s = flambda

speed = wavelength * frequency

where

s is in metres per second m//s

f is in hertz Hz

and lambda is in metres m.

s = flambda can be rearranged as f = s/lambda

here, s = 3 * 10^8 m//s

and lambda = 4.5 * 10^-7 m

s/lambda = (3 * 10^8)/(4.5 * 10^-7)

3/4.5 = 2/3 ~~ 0.667

10^8 / 10^-7 = 10^(8 - -7) = 10^(8+7)

= 10^15

0.667 * 10^15 = 6.67 * 10^14

f = 6.67 * 10^14 Hz