Initially,a photon of wavelength $\lambda_1$ falls on a photocathode and emits an electron of maximum energy $E_1$. If the wavelength of the incident photon is changed to $\lambda_2$,the maximum energy of the electron emitted becomes $E_2$. Then the value of $hc$ ($h=$ Planck's constant,$c=$ velocity of light) is

  • A
    $hc = \frac{(E_1 + E_2) \lambda_1 \lambda_2}{\lambda_2 - \lambda_1}$
  • B
    $hc = \frac{E_1 - E_2}{\lambda_2 - \lambda_1} \cdot (\lambda_1 \lambda_2)$
  • C
    $hc = \frac{(E_1 - E_2)(\lambda_2 - \lambda_1)}{\lambda_1 \lambda_2}$
  • D
    $hc = \frac{\lambda_2 - \lambda_1}{\lambda_1 \lambda_2 E_2} \cdot E_1$

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$A$ photosensitive surface made of cesium on tungsten is irradiated by monochromatic radiation of wavelength $640.2 \ nm$ $(1 \ nm = 10^{-9} \ m)$ from a neon bulb. The measured stopping potential is $0.54 \ V$. If the source is replaced by another source and the same photocell is irradiated by a line of $427.2 \ nm$,what will be the new stopping potential in $V$?

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When a photosensitive material is illuminated by photons of energy $3.1 \ eV$,the stopping potential of the photoelectrons is $1.7 \ V$. When the same photosensitive material is illuminated by photons of energy $2.5 \ eV$,the stopping potential of the photoelectrons is: (in $V$)

The work function of a photoelectric material is $3.3 \text{ eV}$. The threshold frequency will be equal to

Assertion : Photosensitivity of a metal is high if its work function is small.
Reason : Work function $= hf_0$ where $f_0$ is the threshold frequency.

The maximum velocity of an electron emitted by light of wavelength $\lambda$ incident on the surface of a metal of work function $\phi$ is [$h=$ Planck's constant,$m=$ mass of electron and $c=$ speed of light]

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