The Photoelectric Effect - AP Physics 2
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What is the relation between stopping potential and maximum kinetic energy?
What is the relation between stopping potential and maximum kinetic energy?
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Directly proportional. Higher electron kinetic energy requires proportionally higher stopping voltage.
Directly proportional. Higher electron kinetic energy requires proportionally higher stopping voltage.
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What happens if light intensity increases but frequency is constant?
What happens if light intensity increases but frequency is constant?
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More electrons emitted; kinetic energy unchanged. More photons increase electron quantity while frequency determines individual energy.
More electrons emitted; kinetic energy unchanged. More photons increase electron quantity while frequency determines individual energy.
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State the relationship between photon frequency and wavelength.
State the relationship between photon frequency and wavelength.
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$\text{Frequency} \times \text{Wavelength} = c$. Wave equation $c = f\lambda$ relates electromagnetic wave properties.
$\text{Frequency} \times \text{Wavelength} = c$. Wave equation $c = f\lambda$ relates electromagnetic wave properties.
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Convert $2 \text{ eV}$ to joules.
Convert $2 \text{ eV}$ to joules.
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$3.20 \times 10^{-19} \text{ J}$. Using conversion $1 \text{ eV} = 1.6 \times 10^{-19} \text{ J}$.
$3.20 \times 10^{-19} \text{ J}$. Using conversion $1 \text{ eV} = 1.6 \times 10^{-19} \text{ J}$.
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How does light frequency affect the kinetic energy of electrons?
How does light frequency affect the kinetic energy of electrons?
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Higher frequency increases kinetic energy. More energetic photons transfer greater kinetic energy to ejected electrons.
Higher frequency increases kinetic energy. More energetic photons transfer greater kinetic energy to ejected electrons.
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Calculate stopping potential for $E_k = 3 \text{ eV}$.
Calculate stopping potential for $E_k = 3 \text{ eV}$.
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$V_s = 3 \text{ V}$. Maximum kinetic energy in eV numerically equals stopping potential in volts.
$V_s = 3 \text{ V}$. Maximum kinetic energy in eV numerically equals stopping potential in volts.
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What is the unit of frequency?
What is the unit of frequency?
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Hertz (Hz). Standard SI unit for oscillations per second in wave phenomena.
Hertz (Hz). Standard SI unit for oscillations per second in wave phenomena.
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What is the result of increasing the stopping potential?
What is the result of increasing the stopping potential?
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Reduces current to zero. Reverse voltage prevents electrons from reaching collector electrode.
Reduces current to zero. Reverse voltage prevents electrons from reaching collector electrode.
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What happens if the light frequency is below the threshold frequency?
What happens if the light frequency is below the threshold frequency?
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No electrons are emitted. Insufficient photon energy cannot overcome the material's work function.
No electrons are emitted. Insufficient photon energy cannot overcome the material's work function.
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Identify the effect of increasing voltage on the photoelectric current.
Identify the effect of increasing voltage on the photoelectric current.
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Increases current until saturation. Forward voltage accelerates electrons until all available electrons flow.
Increases current until saturation. Forward voltage accelerates electrons until all available electrons flow.
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What is the unit of the work function?
What is the unit of the work function?
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Joules (J). Energy units, since work function represents minimum energy required.
Joules (J). Energy units, since work function represents minimum energy required.
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What does $h$ represent in the photoelectric equation?
What does $h$ represent in the photoelectric equation?
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Planck's constant. Fundamental constant linking energy and frequency: $h = 6.626 \times 10^{-34} \text{ J s}$.
Planck's constant. Fundamental constant linking energy and frequency: $h = 6.626 \times 10^{-34} \text{ J s}$.
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Calculate frequency for wavelength $500 \text{ nm}$.
Calculate frequency for wavelength $500 \text{ nm}$.
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$f = 6.00 \times 10^{14} \text{ Hz}$. Using $f = c/\lambda$ with $\lambda = 500 \times 10^{-9} \text{ m}$.
$f = 6.00 \times 10^{14} \text{ Hz}$. Using $f = c/\lambda$ with $\lambda = 500 \times 10^{-9} \text{ m}$.
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What is the relation between stopping potential and maximum kinetic energy?
What is the relation between stopping potential and maximum kinetic energy?
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Directly proportional. Higher electron kinetic energy requires proportionally higher stopping voltage.
Directly proportional. Higher electron kinetic energy requires proportionally higher stopping voltage.
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What happens if light intensity increases but frequency is constant?
What happens if light intensity increases but frequency is constant?
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More electrons emitted; kinetic energy unchanged. More photons increase electron quantity while frequency determines individual energy.
More electrons emitted; kinetic energy unchanged. More photons increase electron quantity while frequency determines individual energy.
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What is the effect of increasing light frequency on emitted electrons?
What is the effect of increasing light frequency on emitted electrons?
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Increases kinetic energy of electrons. Higher frequency means more energetic photons and faster emitted electrons.
Increases kinetic energy of electrons. Higher frequency means more energetic photons and faster emitted electrons.
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Calculate the photon energy for $f = 6 \times 10^{14} \text{ Hz}$.
Calculate the photon energy for $f = 6 \times 10^{14} \text{ Hz}$.
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$E = 3.98 \times 10^{-19} \text{ J}$. Using $E = hf$ with $h = 6.626 \times 10^{-34} \text{ J s}$.
$E = 3.98 \times 10^{-19} \text{ J}$. Using $E = hf$ with $h = 6.626 \times 10^{-34} \text{ J s}$.
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What effect does increasing light intensity have on photocurrent?
What effect does increasing light intensity have on photocurrent?
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Increases photocurrent. More photons create greater electron flow in photoelectric circuit.
Increases photocurrent. More photons create greater electron flow in photoelectric circuit.
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What is the photoelectric work function symbol?
What is the photoelectric work function symbol?
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$\text{work function}$ or $\text{W}$. Standard symbols representing minimum energy for electron removal from material.
$\text{work function}$ or $\text{W}$. Standard symbols representing minimum energy for electron removal from material.
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How does light frequency affect the kinetic energy of electrons?
How does light frequency affect the kinetic energy of electrons?
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Higher frequency increases kinetic energy. More energetic photons transfer greater kinetic energy to ejected electrons.
Higher frequency increases kinetic energy. More energetic photons transfer greater kinetic energy to ejected electrons.
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Find the work function if $hf = 4 \text{ eV}$ and $E_k = 1 \text{ eV}$.
Find the work function if $hf = 4 \text{ eV}$ and $E_k = 1 \text{ eV}$.
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$\text{work function} = 3 \text{ eV}$. Rearranging Einstein's equation: work function $= hf - E_k$.
$\text{work function} = 3 \text{ eV}$. Rearranging Einstein's equation: work function $= hf - E_k$.
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What is the speed of light in vacuum?
What is the speed of light in vacuum?
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$c = 3.00 \times 10^8 \text{ m/s}$. Fundamental constant for electromagnetic wave propagation in vacuum.
$c = 3.00 \times 10^8 \text{ m/s}$. Fundamental constant for electromagnetic wave propagation in vacuum.
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What is the work function in the photoelectric effect?
What is the work function in the photoelectric effect?
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Minimum energy needed to remove an electron from a material. Material-specific binding energy threshold for electron emission.
Minimum energy needed to remove an electron from a material. Material-specific binding energy threshold for electron emission.
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What is the effect of a higher work function on electron emission?
What is the effect of a higher work function on electron emission?
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Requires higher frequency light to eject electrons. Greater binding energy demands more energetic photons for electron liberation.
Requires higher frequency light to eject electrons. Greater binding energy demands more energetic photons for electron liberation.
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State the relationship between photon frequency and wavelength.
State the relationship between photon frequency and wavelength.
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$\text{Frequency} \times \text{Wavelength} = c$. Wave equation $c = f\lambda$ relates electromagnetic wave properties.
$\text{Frequency} \times \text{Wavelength} = c$. Wave equation $c = f\lambda$ relates electromagnetic wave properties.
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State Einstein's photoelectric equation.
State Einstein's photoelectric equation.
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$E_k = hf - \text{work function}$. Photon energy minus work function equals electron's kinetic energy.
$E_k = hf - \text{work function}$. Photon energy minus work function equals electron's kinetic energy.
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What is the result of increasing the stopping potential?
What is the result of increasing the stopping potential?
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Reduces current to zero. Reverse voltage prevents electrons from reaching collector electrode.
Reduces current to zero. Reverse voltage prevents electrons from reaching collector electrode.
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Identify the threshold frequency symbol.
Identify the threshold frequency symbol.
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$f_0$. Standard notation for minimum frequency required for electron emission.
$f_0$. Standard notation for minimum frequency required for electron emission.
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What does $E_k$ represent in the photoelectric equation?
What does $E_k$ represent in the photoelectric equation?
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Kinetic energy of emitted electrons. Energy of motion possessed by electrons after photoemission occurs.
Kinetic energy of emitted electrons. Energy of motion possessed by electrons after photoemission occurs.
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If $E_k = 0$, what condition holds in the photoelectric equation?
If $E_k = 0$, what condition holds in the photoelectric equation?
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$hf = \text{work function}$. Threshold condition where photon energy exactly equals work function.
$hf = \text{work function}$. Threshold condition where photon energy exactly equals work function.
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