Turning points The Photoelectric effect

Question 1

Describe the characteristics of the photoelectric effect?

Answer 1

Electrons are emitted if the frequency of the incoming uv light is above the threshold frequency.The max Ke of the electrons depends on the frequency of the light.The more intense the light is the more electrons are emitted per second.

Question 2

What does the wave theory predict would happen.

Answer 2

The more intense the light is the more ke the electrons would have.Even if the frequency is below the threshold frequency electrons would be emitted but it would just take longer.The energy spreads out evenly on the wavefront and each free electron would gain some energy.

Question 3

What is quanta?What was the formula?

Answer 3

They are discrete packets that release em waves.E=hf.

Question 4

What did einstein propose?

Answer 4

He proposed that these discrete packets were called photons and had a one to one interaction with the free electrons at the surface of the metal transferring all their energy.

Question 5

What is a black body?

Answer 5

It is a body that absorbs electromagnetic radiation of all wavelengths and can emit electromagnetic radiation of all wavelengths.

Question 6

What was the ultraviolet catastrophe?

Answer 6

Wave theory predicted that power output was proportional to lambda^-4.This meant at the ultraviolet wavelength the power output would be infinity.