Question

The condition for dark fringes in single slit diffraction is given by \[ \sin\theta=\frac{m\lambda}{a} \] In case light from the entire slit arrives at point of observation in phase, for a bright band sine is equal to

• A. $\pm\dfrac{2\lambda}{a}$
• B. 1
• C. 0
• D. $\pm\dfrac{3\lambda}{a}$

Hint:

Central bright fringe occurs at \(\theta=0\).

Answer 1

The Correct Option is C

Concept:
In single slit diffraction, bright fringe occurs when waves from slit interfere constructively.
Step 1:
Dark fringes occur at: \[ a\sin\theta=m\lambda \]
Step 2:
For central maximum, all waves arrive in phase.
Step 3:
At central maximum: \[ \theta=0 \] Thus: \[ \sin\theta=0 \]
Step 4:
\[ \boxed{\sin\theta=0} \] \[ \boxed{\text{Correct Option = (3)}} \]