Photoelectric effect

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Define the Photoelectric effect
The emission of electrons by a solid as a result to exposure to electromagnetic radiation.
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Name two key observations made
The kinetic energy of the photo-electrons depend entirely on the frequency of the radiation. The number of photo-electrons emitted depend entirely on the intensity of the radiation.
2 of 13
State all four of Einstein's postulates
1)Quantisation of light (E=hf) ; 2)The energy is absorbed on an all or nothing bases; 3) When the photon is absorbed all of the energy is delivered; 4) 1 photon to 1 electron
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Define the work function and give an equation
The energy needed to release an electron from the surface of a material/ the potential energy of the outermost electron; W=hf_0=hc/lambda_0
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Give an equation for the Kinetic equation of a photo-electron
E_k=1/2 *m_e *v^2 (where m_e = 9.11*10^-31 kg)
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State two key observations from Millikan's experiment
Increasing the intensity of light increases the saturated current but V_0 stays the same. Changing the frequency of light changes the V_0 but the saturated current. (as frequency of light only changes the energy of the photo-electrons)
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State the key features of the I(photo-current) against V graph formed from the Millikan's Photo-electric experiment
Saturated Current: The maximum current reached as the p.d. increases ;Stopping potential: The potential difference needed to have zero photo-current (to stop the electrons from moving).
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Give equations relating to Millikan's experiment
E_k=1/2 *m(v_max)=eV_0; hf=hf_0 +eV_0; V_0 =h/e *(f-f_0);
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State an application of the photo-electric effect
Photo-electron spectroscopy: the surface analysis for elements and chemical states of the element.
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What is Compton scattering?
The scattering of x-rays from electrons in carbon(graphite) target
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Name the observations made from Compton scattering
It was found that scattered x-rays had a larger wavelengths than those incident on target (there was a decrease in frequency)
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State the equations relating to Compton
lambda_2 - lambda_1 = h/mc *(1-cos(theta)): derived using conservation of momentum and relativistic energy ; h/m_e *c
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Name 4 properties of Photons
1) kinetic mass E/c^2 =h/c*lambda ; 2) momentum= E/c =h/lambda; 3)They are electrically neutral; 4)they are not derailed by magnetic and electric field
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Other cards in this set

Card 2

Front

Name two key observations made

Back

The kinetic energy of the photo-electrons depend entirely on the frequency of the radiation. The number of photo-electrons emitted depend entirely on the intensity of the radiation.

Card 3

Front

State all four of Einstein's postulates

Back

Preview of the front of card 3

Card 4

Front

Define the work function and give an equation

Back

Preview of the front of card 4

Card 5

Front

Give an equation for the Kinetic equation of a photo-electron

Back

Preview of the front of card 5
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