Question

Calculate the wavelength of a light wave whose time period is $3\times {10}^{-10}s$.

• A. $3.3\times {10}^{9}cm$
• B. $3.3\times {10}^{-9}m$
• C. $9\times {10}^{-2}m$
• D. $9\times {10}^{7}cm$

Answer 1

The correct option is C $9\times {10}^{-2}m$

We know,
$c=\nu \lambda$
where $\lambda$ = wavelength of the light wave
So,
$\Rightarrow \nu =\frac{c}{\lambda }$
Time period T = $\frac{1}{\nu }$
$\Rightarrow \frac{1}{T}=\frac{c}{\lambda }$
$\lambda =c\times T=3\times {10}^8\times 3\times {10}^{-10}=9\times {10}^{-2}m$