NEET Physics: Physics Class 12: Optics questions with solutions

Q1. A magnifying glass forms:

1. a real and diminished image
2. a real and magnified image
3. a virtual and magnified image
4. a virtual and diminished image.

Answer: a virtual and magnified image

A magnifying glass is a convex lens used with the object placed closer than its focal length. In that case, the lens forms an upright, virtual, and enlarged image on the same side as the object.

Q2. A point object is placed at a distance \( 10 c m \) and its real image is formed at a distance of \( 20 \mathrm{cm} \) from concave mirror If the object is moved by \( 0.1 \mathrm{cm} \) towards the mirror, the image will shift by about

1. \( 0.4 \mathrm{cm} \) away from the mirror
2. \( 0.4 \mathrm{cm} \) towards the mirror
3. \( 0.8 c m \) away from the mirror
4. \( 0.8 \mathrm{cm} \) towards the mirror

Answer: \( 0.4 \mathrm{cm} \) away from the mirror

For the initial positions, the mirror formula gives the focal length. Then a small movement of the object causes a corresponding image shift found by differentiating the mirror equation. The image moves in the opposite direction and by a smaller amount here, giving 0.4 cm away from the mirror.