Quantum

Question 1

What does Quantum physics explore?

Answer 1

EM radiation and subatomic particles like electrons.

Question 2

Who founded Photons and what are they?

Answer 2

Planck discovered EM is quantised
A ‘packet’ or ‘quantum’ of EM radiation.

Question 3

What does the photon and wave model show?

Answer 3

Photon model - how EMR interacts with matter
Wave model - propagation of waves thro space

Question 4

What is directly proportional to frequency?

Answer 4

Energy of photon
E = hf

Question 5

What equations get E = hc/landa

Answer 5

E =hf
c =flanda

Question 6

What is an electronvolt

Answer 6

1ev is the energy transferred to or from an electron when it moves thro a pd of 1V

Question 7

How to go from Joules to Ev

Answer 7

Divide by 1.6*10^-19

Question 8

How is eV related to J?

Answer 8

From W = VQ = Ve
1 * e = value

Question 9

Explain all points of determining planck constant frm LEDS

Answer 9

• Led only emit at threshold pd
• Potential divide, vary, record, repeat, mean, uncertianity
• Graph V against 1/landa
• m = hc/e
• Calculate h

Question 10

What is the definition of phototelectric effect?

Answer 10

The emission of electrons from the surface of a metal when EM waves with frequency greater than threshold f, are incident on the metal.

Question 11

Give a real life example of Photoelectric effect?

Answer 11

Spacecrafts, interfer with electric components

Question 12

Explain the gold leaf electroscope.

Answer 12

• Zinc plate ontop of negatively charged rod and gold leaf (attached)
• UV light cause effect, leaf retract to centre rod

Question 13

What observations can be made from gold leaf electroscope?

Answer 13

Visible light does not work as photon energy less than work function. intensity dont matter as one to on interaction
UV has required energy, intensity increase rate
Photon energy come frm threshold frequency

Question 14

Why does some photoelectric travel faster?

Answer 14

some electrons need more energy as position to positive ions. More enery for this, less energy for kinetic

Question 15

What was the gold leaf electroscope origionally used for?

Answer 15

measure pd.

Question 16

How do night vision goggles work?

Answer 16

Image intesnifier used effect, metal often semiconductor, suitable work function.

Question 17

Where did Einstiens effect equation come from?

Answer 17

Applied conservation of energy to all.

Question 18

what does f0 mean? What does this mean for equation?

Answer 18

Threshold frequency, zero kinetic enery
hf = @ + KEmax (0)

Question 19

Explain graph used for this Einstiens equation.

Answer 19

Kinetic energy against frequency.
M = h
M same no matter material.

Question 20

Do photons have a charge?

Answer 20

No

Question 21

Do photons travel at the same speed in a vacuum?

Answer 21

Yes

Question 22

Is watts a unit of energy?

Answer 22

No

Question 23

Is kW/h a unit of energy?

Answer 23

yes

Question 24

How does the eney of a photon in glass differ from air.

Answer 24

Is the same.

Question 25

Define Wave-particle duality.

Answer 25

The theory that all objects can exhibit both wave and particle properties.

Question 26

Describe the issue that led to the idea of wp duality.

Answer 26

Interference describes EM radaition as a continuous wave, Photoelectric effect describes it as stream of photons (particles). Idea of wp daulity of nature.

Question 27

What is wave model of light used for? What is it?

Answer 27

Intereference and diffraction. Describes light as oscillating electric and magentic fields perpendicular that propagate through matter or vacuum.

Question 28

What is the particle model of light used for? What is it?

Answer 28

Used to explain photoelectric effect. Light is a steam of discrete packets called photons.

Question 29

Who proposed the WP duality theory?

Answer 29

Louis de Brogile

Question 30

Explain an experiment Broglie did to explain WP theory.

Answer 30

1. Accerated electrons from electron gun at layer of polycrystalline. In vacuum. 2. Circular intereference pattern made 3. Wave like property, but particles

Question 31

Why did Broglie use Polycrystalline?

Answer 31

Diffraction gratings too large for diameter of electrons. Spacing between regularly arrange atoms act as grating.

Question 32

Why was the pattern circular in Broglie's experiment?

Answer 32

The arrangement of the atoms of plycrystalline are diffferent from diffraction gratings.

Question 33

How did Broglie come up with landa = h/p?

Answer 33

Combined E=mc^2 with quantum landa = h/mv mv = p

Question 34

Who tested Broglie's theory?

Answer 34

2 Americans Davisson and Germer.

Question 35

What experiement was done to support Broglie's experiment?

Answer 35

Acclerated electrons frm gun, through pd, to nickel crystal. Circular pattern made.

Question 36

What forumla did these two get for landa again? How?

Answer 36

landa = h/Sqaure root '2mVe' Substituded eV = 1/2mv^2

Question 37

What 2nd thing did Broglie predict? Explain how it was proved.

Answer 37

Varying velocity affects wavelength. Varies speed, Circular rings of patter bigger, shorter wavelength.

Question 38

What can electron dffraction be used for?

Answer 38

Determine inter-atomic spacing.

Question 39

How cna high speed electrons be useful?

Answer 39

Shorter wavelength, can dtermine distance of smaller inter-atomic spacing.

Question 40

What has a inverse relationship with wavelength?

Answer 40

Mass

Question 41

Why do humans not diffract through doors?

Answer 41

Bigger mass, shorter wavelngth, diffraction negligible.

Question 42

Whats the cool sentence?

Answer 42

Intensity at a given point is the probability of a particle being there.

Question 43

Why are x-rays more damaging to cells than some other waves?

Answer 43

Photon energy inversely proportional to wavelngth. Short wavelength, more energy, more damage to cells

Question 44

To get from eV to J, do what?

Answer 44

times 1.6*10^-19

Question 45

What has a typical value of 1.5eV?

Answer 45

Infrared photon.