Question

For a certain light there are $2\times {10}^3$ waves in 1.5 mm in air. The wavelength of light is:

• A. 750 nm
• B. 75$A^{\circ }$
• C. 750$A^{\circ }$
• D. $75\times {10}^7$ m

Answer 1

The correct option is A 750 nm

Given,

Distance, $d=1.5mm=1.5\times {10}^{-3}m$

No. of waves, $n=2\times {10}^{3}nos.$

Wavelength, $\lambda =\frac{\text{distance}}{n}=\frac{1.5\times {10}^{-3}}{2\times {10}^3}=0.75\mu m$

Hence, wave length is $750nm$