EM Radiation and Quantum Phenomena

Question 1

What is a piece of evidence of wave-like properties of electrons?

Answer 1

The diffraction of electrons by a metal crystal

Question 2

What is the equation linking photon energy, Planck’s constant, frequency?

Answer 2

Photon energy = Planck’s constant X Frequency

Question 3

What is needed to remove photoelectrons?

Answer 3

A minimum energy of a photon

Question 4

What does the number of photoelectrons released depend on?

Answer 4

Number of photons per second

Question 5

When an electron collides with an isolated atom, what happens to the colliding electron?

Answer 5

It transfers energy to the atomic electron

Question 6

How is wave property shown?

Answer 6

Diffraction or interference

Question 7

What equation links Photon energy, Planck’s constant, Speed, Wavelength?

Answer 7

Photon energy = (Planck’s constant X Speed) / Wavelength

Question 8

What equation links Photon energy, Emission rate and Power output?

Answer 8

Power output = Photon energy X Emission Rate

Question 9

When comparing two LEDs, what must we consider?

Answer 9

The effect of wavelength on power or emission rate and the maximum emission rate

Question 10

How do you calculate the kinetic energy of a free electron after a collision?

Answer 10

(Kinetic energy at current energy level - Kinetic energy at excited energy level) + Kinetic energy of free electron

Question 11

What is the role of mercury vapour in a fluorescent tube?

Answer 11

It emits photons of UV light following ionisation or excitation

Question 12

Which particle has a greater kinetic energy? Muon or electron?

Answer 12

Muon

Question 13

Which particle has a longer de Broglie wavelength? Muon or electron?

Answer 13

Electron

Question 14

How do atoms gain energy to get excited?

Answer 14

Collision of another particle, giving them enough kinetic energy for excitation, or absorption of photons

Question 15

How do atoms lose energy to get de-excited?

Answer 15

Emission of photons

Question 16

What equation links voltage, charge and work done?

Answer 16

Work done = Charge X Voltage

Question 17

What equation links electrons per second, current and charge?

Answer 17

Electrons per second X Charge = Current

Question 18

What happens to the stopping potential as maximum kinetic energy increases?

Answer 18

Stopping potential increases

Question 19

What must electrons provide to cause excitation?

Answer 19

Enough kinetic energy

Question 20

What does high potential difference produce?

Answer 20

High energy electrons

Question 21

What does coating the tube do to the electrons in the coating?

Answer 21

It excites the electrons as photons are absorbed

Question 22

When is constant current reached?

Answer 22

All photoelectrons released each second reach anode

Question 23

What do photoelectrons lose and gain when potential difference is negative?

Answer 23

They lose kinetic energy and gain potential energy

Question 24

How do you calculate maximum kinetic energy?

Answer 24

Maximum kinetic energy = Photon energy - Work function

Question 25

How do you convert from eV to J?

Answer 25

Divide eV value by 1.6 x 10^-19

Question 26

What equation links kinetic energy, mass, speed?

Answer 26

Kinetic energy = 0.5 x Mass x (Speed)^2

Question 27

What is meant by an antiparticle?

Answer 27

Particle with equal energy and mass but opposite charge, baryon and lepton numbers

Question 28

What type of energy is discrete?

Answer 28

Emitted photon energy

Question 29

How is a photon produced?

Answer 29

When atomic electrons move to lower energy levels

Question 30

What must the kinetic energy of the emitted electrons be compared to the energy of the photons?

Answer 30

The kinetic energy of each must be less than the energy of the photons

Question 31

What would particle behaviour produce?

Answer 31

A patch of light

Question 32

What does graphite cause electron waves to do?

Answer 32

Spread out

Question 33

When does maximum intensity occur?

Answer 33

When waves are in phase

Question 34

What equation links work function, wavelength, speed, kinetic energy, Planck's constant?

Answer 34

Kinetic energy = ((Planck's constant X Speed) / Wavelength) - Work function

Question 35

What is the usual state of an electron in energy level 0?

Answer 35

Free state

Question 36

What is the usual state of an electron in the lowest energy level?

Answer 36

Ground state

Question 37

What needs to be supplied for an electron to be free?

Answer 37

Energy

Question 38

How does a spectrum become visible?

Answer 38

Excited electrons moving into the lower level, which results in photons

Question 39

When an atom de-excites, how much energy will the photon emitted have?

Answer 39

The same as the energy difference between the levels

Question 40

What is the work function?

Answer 40

Minimum energy needed to remove an electron from a surface