A ray of monochromatic light having a wavelength of 4.00 x 10-7 meter in air passes from air through Lucite and then into air again.

1) Calculate the frequency of light in air.

2) Identify the color of the light.

wavelength of light = 4 x 10⁻⁷ m

frequency = velocity in air / 4 x 10⁻⁷

= 3 x 10⁸ / 4 x 10⁻⁷

=.75 x 10¹⁵ Hz

= 75 x 10¹³ Hz.

Wave length = 4 x 10⁻⁷ m

= 400 x 10⁻⁹m

400 nm

colour of light having this wavelength in air is violet.