Q177 / 225 · JEE Main 2002 · Physics

Sodium and copper have work functions $2.3 \mathrm{eV}$ and $4.5 \mathrm{eV}$ respectively. Then the ratio of the wave lengths is nearest to

  • A
    1 : 2
  • B
    4 : 1
  • Correct answer
    C
    2 : 1
  • D
    1 : 4

Solution

$\mathrm{hc} / \lambda_0=\mathrm{W}_0 ; \frac{\left(\lambda_0\right)_1}{\left(\lambda_0\right)_2}=\frac{\left(\mathrm{W}_0\right)_2}{\left(\mathrm{~W}_0\right)_1}=\frac{4.5}{2.3}=2: 1$

Hence, the correct answer is option: 'C'.

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