Photons and electrons

Question 1

Define Frequency:

Answer 1

Frequency is the number of complete waves that pass a point per second.

Question 2

Define Wavelength:

Answer 2

Wavelength is the distance between two consecutive points on a wave that are in phase.

Question 3

What is the Photoelectric effect?

Answer 3

The Photoelectric effect is the process that occurs when light shines on a metal and electrons are ejected.

Question 4

What is the significance of the Photoelectric effect?

Answer 4

The Photoelectric effect establishes the quantum theory and it illustrates the particle nature of light.

Question 5

Define a photon:

Answer 5

A photon is the quantum of energy when the energy is in the form of electromagnetic radiation.

Question 6

What is the threshold frequency?

Answer 6

The threshold frequency is the minimum frequency of incident radiation at which electrons will be emitted from a particular metal.

Question 7

What is the work function of a metal?

Answer 7

The work function of a metal is the minimum amount of energy needed to emit an electron from the surface of a metal.

Question 8

Define red shift:

Answer 8

Red shift is a shift in the spectra of distant galaxies toward longer wavelengths, i.e. towards the red end of the spectrum.

Question 9

What is an absorption spectrum?

Answer 9

An absorption spectrum is produced when white light from a source passes through a “cool”
gas.

Question 10

What is an emission spectrum?

Answer 10

An emission spectrum is produced when electrons “fall” from an orbital of higher energy to
an orbital of lower energy.