Why might blue light cause emission of electrons from metal while red light does not?

Answer 1

Blue light will eject electrons from a photosensitive surface because blue light has a high frequency. The high photon frequency of the blue light means it has more energy because the frequency is directly linked to the energy of the photons. Red light would not eject electrons because it has a low frequency.

Answer 2

Using the formula:

photon energy (E) = Planck constant (h) * frequency (Æ’) Blue has a higher frequency than red. Since h is constant, E increases as Æ’ increases.

Using the formula:

photon energy (E) = Planck constant (h) * speed of light (c) / wavelength (λ)

Blue has a shorter wavelength than red. Since h and c are considered constant, E increases as λ decreases.

Answer 3

Blue light will eject electrons from a photosensitive surface because blue light has a high frequency. The high photon frequency of the blue light means it has more energy because the frequency is directly linked to the energy of the photons. Red light would not eject electrons because it has a low frequency.

Answer 4

In order to eject an electron from an atom, sufficient energy is required. Photons of blue light are more energetic than photons of red light.

(It's possible that two photons of red light could collectively supply enough energy to eject an electron, but this kind of concerted mechanism would be quite rare.)

Answer 5

The principle of the matter goes like this:

-- It takes a certain amount of energy for an electron to break free of the atom

to which it's bound.

-- Electrons can't save up a little bit of energy that comes in now and some more

energy that arrives later until it has enough to make the break. It has to get the

amount of energy it needs all at once, in a single shot.

-- A photon of red light doesn't have enough energy to enable the electron to

escape. It doesn't matter how bright the red light is. That just means there are

more photons. But each photon still has the same energy, and the electron can't

put together the energy from two of them. It needs to get it all in one gulp.

-- A photon of blue light has more energy than a photon of red light. So it

doesn't matter how dim the blue light is. That just means there are fewer

photons. But each and every one of them has enough energy to enable the

electron to break free of its atom.

This was the work that got Albert Einstein his first Nobel Prize.

Answer 6

Blue light has higher energy than red light., E=hf. There is a minimum energy necessary to emit an electron from metal and red light is below that minimum.