Question

In Young's double slit experiment the y-coordinates of central maxima and 10^th maxima are 2 cm and 5 cm respectively. When the YDSE apparatus is immersed in a liquid of refractive index 1.5, the corresponding y-coordinates will be

• A. 2 cm, 7.5 cm
• B. 3 cm, 6 cm
• C. 2 cm, 4cm
• D. 4/3 cm, 10/3 cm

Answer 1

Answer: (C)

2 cm, 4cm

Answer 2

After immersing, no change in central maxima in air, separation between central maxima & 10^th maxima = 5cm –2cm = 3cm = $10\frac{D\lambda}{d}$ in liquid, separation between central maxima & 10^th maxima = $10\frac{D\lambda'}{d}$=$10\frac{D}{d}\frac{\lambda}{\mu}$ $= \left( \frac{10D\lambda}{d} \right)/1.5$ = $\frac{3cm}{1.5} = 2cm$. So new co-ordinate of 10^th maxima = 2cm + 2cm = 4cm