JEE Main · 2023 · 11 Apr 2023 · Shift 2 · Geometrical Optics

The bulb at the bottom of the water appears to be at an apparent depth when viewed from air. The apparent depth is $d^{\prime }=\frac{d}{\mu }=\frac{8}{4/3}=6$ cm from the water surface. The mirror is 50 cm above the bottom, so it is $50-8=42$ cm above the water surface. The apparent position of the bulb is $42+6=48$ cm below the mirror. The mirror forms an image 48 cm behind it, which is $48+50=98$ cm from the bottom of the tank.