Chapter 3 - Quantum phenomena

Question 0

What is the formula relating work function, frequency and the maximum kinetic energy

Answer 0

Ek=hf-phi

Question 1

Define the term photoelectricity

Answer 1

Emissions of electrons from a metal surface when illuminated by a light greater than the threshold frequency

Question 2

Define the term work function

Answer 2

The minimum amount of energy required for an electron to escape from the metal surface

Question 3

What is the formula relating current and the number of photoelectrons emitted per second?

Answer 3

current=number of photoelectrons emitted per second * charge of an electron

Question 4

How can you plot hf=phi+Ek on a graph?

Answer 4

rearrange to Ek=hf - phi

so y =mx+ c

Question 5

Explain why the intensity of light doesn’t affect the maximum kinetic energy of a photoelectron given it exceeds the threshold frquency

Answer 5

Each individual electrons absorbs 1 photon

Question 6

Define the term electron volt

Answer 6

the work required to move an electron through 1 p.d.

Question 7

When an electron is hit with an incident electron but isn’t excited/ionised how much energy does the electron have?

Answer 7

The same amount

Question 8

Define the term excitation energies

Answer 8

The energy values at which an atom absorbs energy

Question 9

What is the ground state also known as?

Answer 9

n=1

Question 10

When an electron de-excites what is the energy of the emitted photon

Answer 10

hf = E1-E2

Question 11

What do raindrops and prisms split white light into?

Answer 11

A continuous spectrum

Question 12

How can you produce a discrete spectrum?

Answer 12

Use a glowing gas as the light source

Question 13

What does de-excitation release?

Answer 13

A photon

Question 14

Define wave-particle duality of light

Answer 14

Light can behave like particles or waves

Question 15

When does light behave like a wave?

Answer 15

Diffraction, refraction, reflection

Question 16

When does light behave like a particle?

Answer 16

The photoelectric effect, excitation, ionisation

Question 17

Explain why discrete light spectrums are unique to that element

Answer 17

The energy levels are unique to that element; photons emitted are a characteristic of the element

Question 18

What is the formula relating wavelength and momentum/ mass and velocity? (Used for matter particles)

Answer 18

lambda = h/p = h/mv

Question 19

What is the formula for de Broglie’s wavelength? (used for matter particles)

Answer 19

lambda = h/p = h/mv

Question 20

Matter particles have a wave particle nature, what formula can you use to work out the wavelength?

Answer 20

de Broglie’s wavelength formula