Question

In diffraction experiment, from a single slit, the angular width of central maximum does NOT depend upon

• A. ratio of wavelength and slit width
• B. distance of the slit from the screen
• C. wavelength of light used
• D. width of the slit

Hint:

Don't confuse "angular width" with "linear width." Linear width increases as the screen is moved further away, but angular width—the angle subtended at the slit—remains constant.

Answer 1

The Correct Option is B

Step 1: Recall the angular width.
For a single slit, the central maximum spreads over an angle $\theta = \tfrac{2\lambda}{a}$, where $\lambda$ is the wavelength and $a$ the slit width.

Step 2: See what enters the formula.
This formula has only $\lambda$ and $a$ in it, so the angular width depends on the wavelength, the slit width, and their ratio.

Step 3: Spot what is missing.
The screen distance $D$ never appears. It changes the linear size of the bright band, but not the angle.

Step 4: Pick the odd one out.
So angular width does not depend on the distance of the slit from the screen. \[ \boxed{\text{Distance of the slit from the screen}} \]