Quantum physics

Question 1

The energy, E of a photon is equal to

Answer 1

hf or hc/lambda, c being the speed of light and h being planck’s constant

Question 2

What is planck’s constant?

Answer 2

6.63 times ten to the negative 34

Question 3

What is the speed of light?

Answer 3

3 times ten to the 8

Question 4

What is an electron volt defined as?

Answer 4

energy transferred when an electron travels through a potential difference of one volt

Question 5

An electron volt is equal to

Answer 5

1.6 times ten to the negative 19

Question 6

The photoelectric effect

Answer 6

When EM radiation is shone on to a metal, electrons are released from the surface of the metal, the emission occurs almost instantly

Question 7

What is the work function of a metal?

Answer 7

the minimum energy required to free an electron from the surface of the metal, each photon must have energy as great as the work function to release an electron

Question 8

What is the threshold frequency?

Answer 8

Minimum frequency required to free electrons from the surface of the metal. UV light has a greater threshold frequency than visible light which is why it produces the photoelectric effect and the latter doesn’t

Question 9

What is the photoelectric equation?

Answer 9

hf= work function plus KEmaxx

Question 10

What is KEmax?

Answer 10

The maximum amount of kinetic energy of the released electron

Question 11

Why is kinetic energy a maximum?

Answer 11

Some electrons may be closer to the nucleus requiring more energy than the work function amount to be released

Question 12

What happens when the incident radiation has frequency below the threshold frequency?

Answer 12

No electrons will be released regardless of the intensity of the radiation

Question 13

What happens when the incident radiation has a frequency above the threshold frequency?

Answer 13

Electrons will be released and increasing the intensity of the radiation will increase the rate of electron emission. because the the increase in intensity increases the number of photons available to interact with electrons

Question 14

What is the only way to increase the Kinetic energy of the electrons

Answer 14

Increase the frequency of radiation above the threshold frequency so there is more energy left over to turn into kinetic energy

Question 15

What does De Broglie say?

Answer 15

All matter can exhibit both wave and particle properties and that the wavelength associated with a particle is inversely proportional to its momentum, wave-particle duality

Question 16

What equation is the wavelength is inversely proportional to momentum relationship shown by?

Answer 16

lambda is equal to h/p which is equal to h/mv

Question 17

How do electrons present wave-particle duality behaviour?

Answer 17

When electrons are fired at a thin piece of polycrystalline graphite which is a material containing carbon atoms spread over many layers, the electrons are diffracted by the gaps between atoms and produce diffraction pattern when they hit a screen

Question 18

When do LEDS emit light?

Answer 18

When the potential difference across them exceeds the threshold pd required

Question 19

Order of EM waves,

red monkeys in visible under x game

Answer 19

Radio
Microwave
infrared
Visible
UV
X-ray
Gamma

Question 20

What would happen if we were to use visible light for the photoelectric effect?

Answer 20

No electrons are emitted as the photon energy is below the work function

Question 21

what is the difference between the photon and the electron in regards to the photo electric effect?

Answer 21

Photons are shone on the metal and electrons are emitted, there is a one to one interaction between them

Question 21

Why is one eV equal to 1.6 times ten to the negative 19?

Answer 21

W=VQ and one volt times the charge is 1.6 times ten to the negative 19

Question 22

What is the typical wavelength of radio wave?

Answer 22

to the one

Question 23

What is the wavelength of infrared?

Answer 23

the minus 5

Question 24

What is the wavelength of visible

Answer 24

the minus seven

Question 25

What is the wavelength of UV?

Answer 25

-7

Question 26

What is the wavelength of X-ray?

Answer 26

-9

Question 27

What is the wavelength of gamma?

Answer 27

-13