Question

A metal foil has a threshold frequency of 5.45×1014 hz . Which of the colors of visible light have enough energy to eject electrons from this metal?

Answer 1

Answer:

Green, blue, indigo and violet.

Explanation:

The velocity of a wave is given by

$v=f\lambda$

where

f = Frequency = $5.45\times 10^{14}\ Hz$

$\lambda$ = Wavelength

$\lambda=\frac{v}{f}\\\Rightarrow \lambda=\frac{3\times 10^8}{5.45\times 10^{14}}\\\Rightarrow \lambda=5.50459\times 10^{-7}\ m=550.459\times 10^{-9}\ m\\ =550.459\ nm$

The wavelength of the wave is 550.459 nm

Green light has wavelength which ranges from 500-565 nm.

So, the light which observed is green light and  lower in wavelength than green light i.e., green, blue, indigo and violet.