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Physics > Topic 5: Particle model of light > Flashcards

Topic 5: Particle model of light Flashcards

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1
Q

What is a photon

A

A small packet of energy

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2
Q

What is wave particle duality

A

The idea that electrons can act as both a wave and a particle

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3
Q

Define wave phenomena

A

all the things that only waves can do

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4
Q

What are the 4 types of wave phenomena

A

Reflection,Refraction,Diffraction interference

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5
Q

What is planks constant

A

6.63x10-34

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6
Q

What two phenomena prove that Waves act as a particle

A

The photoelectric effect
Line spectra

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7
Q

What is planks constant theory

A

The idea that electromagnetic radiation is emitted is very small and the higher the frequency the higher the energy

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8
Q

What is the derivation for planks constant

A

E=∝f
E=kf
E=hf

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9
Q

What is work function

A

The minimum amount of energy required to release one electron from its ionic lattice in a metal

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10
Q

What is the threshold frequency

A

when the work function is equal to the photon energy

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11
Q

What is the equation for The energy of a photon

A

E=hf

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12
Q

What is the photoelectric equation

A

Hf=Φ +ke

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13
Q

What is the de broglie wavelength

A

λ=h/mv

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14
Q

define de broglie wavelength

A

Any particle with a momentum has an associated wavelength

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15
Q

Define the stopping potential

A

The work done against the electrons to cancel out the Kinetic energy

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16
Q

What is the exitation energy

A

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

17
Q

What is the ionisation energy

A

The amount of energy an electron needs to ionise and break free from its lattice

18
Q

What is the photoelectric effect

A

Proof that light has a particle nature

19
Q

Why is the wave theory for the photoelectric effect incorrect

A

Wave theory states that the longer the light is shone on the metal the more energy it has

Eventually low intensity light will still release enough electrons as it will build up energy

20
Q

Explain the photoelectric effect

A

Electrons trapped in ionic lattice of metal due to positive charge

Electrons get energy from light waves in order to ionise and escape the metal

Once the electrons escape any residual energy is converted into kinetic energy as it it leaves the metal

21
Q

Which need less energy to escape electrons closer to the top of the metal or the middle

A

Top

22
Q

How many experimental findings are their for the photoelectric effect?

A

3

23
Q

How do you convert from EV to J

A

/ 1.6x10-19

24
Q

How do you convert from J to EV

A

x 1.6 x10-19

25
Q

What is the gradient on a photoelectric graph

A

Planks constant

26
Q

What is the y intercept on a photoelectric graph

A

Work function

27
Q

what is the X axis on a photoelectric graph

A

Frequency

28
Q

what is the Y axis on a photoelectric graph

A

Kinetic energy

29
Q

What is the point at which the Kinetic energy is 0 on the graph

A

The fundamental frequency

30
Q

What is the equation for stopping potential

A

work done =kinetic energy
VQ=1/2MV^2

31
Q

What can the stopping distance be used for (3)

A

helps to find the kinetic energy of something small as e-
Can vary frequency & see how it affects KE
find the threshold frequency and work done

32
Q

What is a photo vacuum cell

A

A component containing a photocathode and an anode that can produce photoelectrons.

33
Q

Explain how a photo vacuum cell works

A
34
Q

Explain how a photo vacuum cell works with a cell to generate a stopping potential

A

When a cell is added to produce a voltage in the opposite direction to the flow of the photoelectrons. When this voltage is high enough it can be used to stop the flow of photoelectrons. this us the stopping potential which we can use to measure the amount of photoelectrons we have in a a current.

35
Q
A

Physics (10 decks)

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