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A metal of work function 2.5 eV is irrad...

A metal of work function 2.5 eV is irradiated by light. If the emitted electrons have maximum kinetic energy 1.8 eV, then the energy of irradiating light is

A

0.7 eV

B

3.8 eV

C

4.3 eV

D

4.8 eV

Text Solution

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The correct Answer is:
To solve the problem, we will use the photoelectric equation, which relates the maximum kinetic energy of emitted electrons to the energy of the incident light and the work function of the metal. The equation is given by: \[ KE_{max} = E_{incident} - \phi \] Where: - \( KE_{max} \) is the maximum kinetic energy of the emitted electrons. - \( E_{incident} \) is the energy of the incident light. - \( \phi \) is the work function of the metal. ### Step-by-Step Solution: 1. **Identify the given values**: - Work function (\( \phi \)) = 2.5 eV - Maximum kinetic energy (\( KE_{max} \)) = 1.8 eV 2. **Write the photoelectric equation**: \[ KE_{max} = E_{incident} - \phi \] 3. **Rearrange the equation to find the energy of the incident light**: \[ E_{incident} = KE_{max} + \phi \] 4. **Substitute the known values into the equation**: \[ E_{incident} = 1.8 \, \text{eV} + 2.5 \, \text{eV} \] 5. **Perform the addition**: \[ E_{incident} = 4.3 \, \text{eV} \] 6. **Conclusion**: The energy of the irradiating light is **4.3 eV**.

To solve the problem, we will use the photoelectric equation, which relates the maximum kinetic energy of emitted electrons to the energy of the incident light and the work function of the metal. The equation is given by: \[ KE_{max} = E_{incident} - \phi \] Where: - \( KE_{max} \) is the maximum kinetic energy of the emitted electrons. - \( E_{incident} \) is the energy of the incident light. - \( \phi \) is the work function of the metal. ...
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Knowledge Check

  • A light of intensity 16 mW and energy of each photon 10 eV incident on a metal plate of work function 5 eV and area 10^(-4)m^(2) then find the maximum kinetic energy of emitted electrons and the number of photoelectrons emitted per second if photon efficiency is 10% .

    A
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    B
    10 eV, `10^(12)`
    C
    5 eV, `10^(13)`
    D
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  • The work function of a metal is 3.4 eV. A light of wavelength 3000Å is incident on it. The maximum kinetic energy of the ejected electron will be :

    A
    `1.18 xx 10^(-19)J`
    B
    `2.36 xx 10^(-19)J`
    C
    `3.4 xx 10^(-19)J`
    D
    Electron will not be ejected
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    B
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