Quantum
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Last updated 1:43 PM on 6/19/23
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23 Terms
1
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what is Photoelectric effect?
Where one free electron on a metal's surface absorbs energy from one photon
2
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What is the emitted electron called?
Photoelectron
3
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What happens if the frequency is enough (>threshold frequency) + the energy is enough (>work function)?
The electron is released
4
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what is 1eV equivalent to in joules?
1\.6x10^-19 J
5
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Unit for electron energy ?
Electron volt (eV)
6
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What is 1eV (definition) ?
The energy transferred when an electron travels through a potential difference of 1 volt.
7
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h x f =
Φ + Ek (max)
8
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What is Work function ?
Minimum energy to remove electron from the metal's surface
9
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What is Threshold frequency?
Minimum frequency needed to remove an electron from the metals surface
10
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At the minimum threshold to free an electron: kinetic energy = what ?
0
11
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The gradient of a KE:f graph = what ?
Planck's constant
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How can a circuit be used to find the maximum kinetic energy for photoelectrons?
* A potential difference is increased in the opposite direction to the way the electrons are moving.
* When the electrons just fail to reach the anode, the stopping potential has been reached.
* Ek(max) = eV(stop)
* When the electrons just fail to reach the anode, the stopping potential has been reached.
* Ek(max) = eV(stop)
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What is the excess energy in photoelectric effect called ?
kinetic energy
14
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What is Excitation?
Electrons moving up energy levels
15
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What is De-excitation ?
Electrons moving down energy levels
16
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What does Change in Energy = ?
Planck's constant x frequency
17
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What is Ionisation ?
The electron escapes completely from the top energy level of the atom
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What is Ionisation energy ?
The minimum energy needed to completely free an electron from an atom
19
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How else can we ionise gas atoms?
By applying a voltage
20
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How do fluorescent lights work?
They generate UV radiation which is absorbed (mercury vapour) and re emitted as visible light by a layer of phosphorus inside the bulb
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(De Broglie) wavelength = ?
Planck's constant / momentum
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Electrons interfere in a ____ _________ pattern.
Wave interface
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Greater momentum (from faster electrons) means ?
Smaller de Broglie wavelength
