The work function for tungsten and sodium are 4.5 eV and 2.3 eV r… - Vidyadip

MCQ

The work function for tungsten and sodium are $4.5 \mathrm{eV}$ and $2.3 \mathrm{eV}$ respectively. If the threshold wavelength $\lambda$ for sodium is $5460 \mathring A$, the value of $\lambda$ for tungsten is

A
$5893 \mathring A$
B
$10638 \mathring A$
✓
$2791 \mathring A$
D
$528 \mathring A$

✓

Answer

Correct option: C.

$2791 \mathring A$

$ \text { Since } W_0=\frac{h c}{\lambda_0} ; \therefore \frac{\left(W_0\right)_T}{\left(W_0\right)_{N a}}=\frac{\lambda_{N a}}{\lambda_T} \text { or} $
$ \lambda_T=\frac{\lambda_{N a} \times\left(W_0\right)_{N a}}{\left(W_0\right)_T}=\frac{5460 \times 2.3}{4.5}=2791 \mathring A$

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