Question

Figure here shows a wavefront of light of wavelength l incident normally on a slit of width d. For a distant observation point at inclination q, the disturbances from the ends A and B are represented by the 'amplitude vectors' (phasors) P and Q respectively. The angle Df is given by _

• A. $\left( \frac{d}{\lambda} \right)$sinq
• B. $\left( \frac{2\pi d}{\lambda} \right)$cosq
• C. $\frac{2\pi}{\lambda}$d sin q
• D. $\frac{2\pi}{\lambda}$ d tan q

Answer 1

Answer: (C)

$\frac{2\pi}{\lambda}$d sin q

Answer 2

There different : $\frac{2.5}{\lambda}$ (d sin q)