Question

The fringe width for red colours as compared to that for violet colour is approximately

• A. 3 times
• B. 2 times
• C. 4 times
• D. 8 times

Answer 1

The correct option is B 2 times

$\beta =\lambda \frac{D}{d}$

${\lambda }_{red}$ is approximately twice ${\lambda }_{violet}$

So $\frac{{\beta }_{red}}{{\beta }_{violet}}=2:1$

Answer. B) 2 times