Question

Photoelectrons are ejected from a metal when exposed to 238-nm radiation, but no photoelectrons are observed when the metal is exposed to 265 nm radiation. Which of the following is true?

a. No photoelectrons will be ejected if the metal is exposed to 285 nm radiation.

b. 226 nm radiation will cause a greater number of photoelectrons to be ejected from the metal.

c. No photoelectrons will be ejected if the metal is exposed to 253 nm radiation.

d. 253 nm radiation will cause photoelectrons to be ejected from the metal.

Answer 1

Since 238 nm ejects photo electron, all wavelength less than 238 nm should also be able to eject electrons.

Since 265 nm do not eject photo electron, all wavelength greater than 265 nm should not be able to eject electrons.

Nothing can be said about the wavelengths between 238 nm and 265 nm.

a. No photoelectrons will be ejected if the metal is exposed to 285 nm radiation.

So, This is true

b. 226 nm radiation will cause a greater number of photoelectrons to be ejected from the metal.

The number of electrons do no depends on the wavelength.

It depends on the number of photons.

So, This is false

c. No photoelectrons will be ejected if the metal is exposed to 253 nm radiation.

Nothing can be said about the wavelengths between 238 nm and 265 nm.

d. 253 nm radiation will cause photoelectrons to be ejected from the metal.

Nothing can be said about the wavelengths between 238 nm and 265 nm.

Answer: a