1. Tardigrade
  2. Question
  3. Physics
  4. A photoelectric current emerging in the circuit of a vacuum photocell when its zinc electrode is subjected to electromagnetic radiation of wavelength 262 nm is cancelled if an external decelerating voltage 1.5 V is applied. Find the magnitude of outer contact potential difference of the given photocell. Work function of zinc metal is 3.74 eV.

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Q. A photoelectric current emerging in the circuit of a vacuum photocell when its zinc electrode is subjected to electromagnetic radiation of wavelength $262\, nm$ is cancelled if an external decelerating voltage $1.5 \,V$ is applied. Find the magnitude of outer contact potential difference of the given photocell. Work function of zinc metal is $3.74\, eV$.

Dual Nature of Radiation and Matter

Solution:

$\phi=3.74\, eV \lambda=262 \,nm$
energy of photon $=\frac{1242\, n\,meV }{262\, nm }=4.74\, eV$
$K _{\max }= eV _{ s }= hv -\phi$
$eV _{ s }=4.74-3.74=1 \,eV$
stopping potential $=1$ volt
decelerating voltage $- V _{ B }=1.5 \,V -1 \,V$
$=0.5\, V$
$\Rightarrow$ outer contact P.D. $=0.5 \,V$