MCQ
Monochromatic radiation emitted when electron on hydrogen atom jumps from first excited to the ground state irradiates a photosensitive material. The stopping potential is measured to be $3.57 \;V$. The threshold frequency of the material is .........$ \times 10^{15}\; Hz$
  • A
    $2.5$
  • $1.6$
  • C
    $4$
  • D
    $5$

Answer

Correct option: B.
$1.6$
b
Energy released from emmition of electron is $E =(-3.4)-(-13.6)=10.2 eV$.

From photo-electric equation, work function $\phi= E - eV = h v _0$

On Solving this $v _0=1.6 \times 10^{15} Hz$

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