what is the correct answer choice?

Question

You fire a beam of light at a piece of metal and determine that electrons are emitted with 2.0 eV of energy. You increase the wavelength of the light and determine that electrons are still being emitted. What else is true?

Group of answer choices

there is an increase the speed of the emitted electrons.

there is a decrease the speed of the emitted electrons.

there is an increase the number of electrons emitted.

there is a decrease the number of electrons emitted.

Answer 1

The energy of light photons is given by the relation E = hc/λ where h is planck's constant, c the speed of light and λ the wavelength. As you can see the photon energy is inversely related to the wavelength, so as the wavelength gets longer, the energy decreases.

If the energy of the photons gets smaller, the kinetic energy and the velocity of the emitted electrons decreases. Answer b is correct.