EM radiation and Quantum phenomenon

Question 1

What proves that waves are particles/act like particles

Answer 1

Photoelectric effect

Question 2

what is the photoelectric effect

Answer 2

When EM radiation above a certain frequency is shone on metal causing electrons to be emitted

Question 3

How does the photoelectric effect work

Answer 3

Metals contain free electrons. When EM radiation above the threshold frequency is shone onto the metal. The electrons absorb the energy causing them to vibrate and break free from the metal bond holding the electron and causing it to be emitted.

Question 4

When are electrons emitted from the metal

Answer 4

when the EM radiation has a frequency at or above the threshold frequency value

Question 5

What is the kinetic energy when the electrons are emitted

Answer 5

A range of values depending on the frequency of EM radiation used

Question 6

What is the intensity of radiation?

Answer 6

The amount of radiation hitting an area of metal per second

Question 7

What are photoelectrons

Answer 7

The name for electrons emitted by the photoelectric effect

Question 8

How do you calculate the number of photoelectrons per second

Answer 8

It is proportional to the intensiity of the radiation

Question 9

What evidence is there that disproves that waves are based of of the wave theory

Answer 9

The threshold frequency - frequency is directly proportional to energy. so a lower frequency over a period of time would equal to the same energy transfer such a wave with a higher frequency over a shorter period of time. But that doesn’t happen. so wave theory can not explain threshold frequency

Kinetic energy - Kinetic energy of a photon should increase with intensity as more energy should be transfered per second. Wave theory can not explain why energy is solely based on the frequency

Question 10

What did einstein suggest about EM waves

Answer 10

He said that EM waves exist in wave-packets called photons

Question 11

How do photons have interactions with electrons

Answer 11

One on one particle like interactions where 1 photon would transfer all of its energy to a singular electron only.

Question 12

what is the work function

Answer 12

the energy needed to break the bond holding the electron to the metal

Question 13

what happens when the energy gained by an electron is less than the work function

Answer 13

The metal will heat up as the particle vibrates but isn’t emitted

Question 14

What is the stopping potential

Answer 14

The potential difference needed to apply to stop the fastest electrons with Ek (max) as the electrons lose their energy by doing work against a potential difference

Question 15

How do electrons in atoms exist

Answer 15

They exist in energy levels in atoms

Question 16

How does an electron move to a higher energy level

Answer 16

By absorbing a photon

Question 17

How does an electron move down to a lower energy level

Answer 17

By emitting a photon

Question 18

What is an electron volt

Answer 18

The kinetic energy of an electron gained by electron after it has been accelerated by 1 volt

Question 19

how do you number energy levels

Answer 19

The ground state is n=1 and everything above that is n+1

Question 20

Why is the energy in energy level diagrams negative

Answer 20

That is the energy needed to overcome to reach 0 energy as 0 energy is when a particle

Question 21

what is ground state

Answer 21

The lowest energy state an electron can be in

Question 22

what is ionisation energy

Answer 22

The energy required to remove an electron from the ground state atom

Question 23

How can you find the ionisation energy

Answer 23

it is the energy next to the n’s in an energy level diagram

Question 24

what is ionisation

Answer 24

When an atom gains or loses an electron

Question 25

what is excitation

Answer 25

when an electron moves up energy levels/level

Question 26

How do fluorescent tubes work

Answer 26

The tube contains mercury vapour. When current is run through the mercury vapour, the mercury atoms get ionised emitting electrons. These electrons collide with mercury electrons in energy levels causing the electrons to get excited. The electrons soon get de-excited releasing the energy gained in the collision as a photon of UV light. This photon gets absorbed by the fluorescent coating. The electrons in the coating absorb the photons and get excited and get de-excited emitting a photon of visible light.