Question

A linear aperture whose width is $0.02\, cm$ is placed immediately in front of a lens of focal length $60\, cm$. The aperture is illuminated normally by a parallel beam of wavelength $5 \times 10^{-5} cm$. The distance of the first dark band of the diffraction pattern from the centre of the screen is

• A. 0.10 cm
• B. 0.25 cm
• C. 0.20 cm
• D. 0.15 cm

Answer 1

The Correct Option is D

Calculation Explanation

The correct option is (D): 0.15 cm. 

Step-by-Step Calculation:

We are given the following equation:

\(x = \frac{5 \times 10^{-5} \times 60}{0.02}\)

Now, perform the multiplication in the numerator:

\(x = \frac{300 \times 10^{-5}}{0.02}\)

Next, simplify the expression:

\(x = 0.15 \, \text{cm}\)

Conclusion:

The calculated value of \( x \) is 0.15 cm.