PARTICLES AND WAVES - The photoelectric effect, quantum theory of light and interference

Question 1

What is photoemission

Answer 1

The emission of electrons when electromagnetic radiation strikes a metal surface

Question 2

What factors determine whether or not photoemission will take place

Answer 2

The frequency/wavelength of the electromagnetic radiation and the type of metal on which the radiation is incident

Question 3

What causes the leaf on the electroscope to fall

Answer 3

Photoelectrons being emitted from the metal plate

Question 4

What is meant by threshold frequency

Answer 4

The threshold frequency is the minimum frequency of a photon required for photoemission

Question 5

what is the work function of metal

Answer 5

the minimum energy required to cause photoemission

Question 6

what determines the maximum kinetic energy of a photoelectron

Answer 6

The kinetic energy of a photoelectron depends only upon the frequency or wavelength of the radiation absorbed and the work function (type of metal involved)

Question 7

What is meant by constructive interference

Answer 7

Wave meet in phase i.e crest meets crest

Question 8

what is meant by destructive interference

Answer 8

waves meet out of phase i.e crest meets trough

Question 9

Describe the conditions required for 2 wave sources to be coherent

Answer 9

The 2 wave sources must have a constant phase difference and have the same wavelength, frequency and velocity

Question 10

What is meant by path difference

Answer 10

The extra distance travelled by on e wave source compared to anther wave source