LIGHT REFLECTION &REFRACTION

A student while determining the focal length of the given convex lens, obtains on the screen the image of a distant object. With respect to the object the image formed on the screen will be

• Inverted and enlarged

• Erect and enlarged

• Erect and diminished

• Inverted and diminished

Three students A, B and C focussed a distant building on a screen with the help of a concave mirror. To determine focal length of the concave mirror they measured the distances as given below : Student A : From mirror to the screen Student B : From building to the screen Student C : From building to the mirror Who measured the focal length correctly :

• Only A

• Only B

• A and B

• B and C

Which of the following lenses would you prefer to use while reading small letters found in a dictionary?

• A convex lens of focal length 50cm

• A concave lens of focal length 50cm

• A convex lens of focal length 5 cm

• A concave lens of focal length 5 cm

Radius of curvature of a spherical mirror is 20 cm. Whats is itsfocal length.

• 10cm

• 40cm

• 5cm

• 20cm

Power of the convex lens having a focal length 25cm is:

• 4D

• 0.2D

• 2.5D

• 40D

Rays from sun converges to a point at 15 cm in front of a concave mirror.Find its focal length.

• 30cm

• 15cm

• Infinity

• None of the above

No matter how far you stand from a mirror, your image appears erect. The mirror is likely to be :

• Plane

• Concave

• Convex

• Either plane or convex

Name the lens that can form both real and virtual image.

• Convex

• Concave

• Concavoconvex

• None

Rays from sun converges to a point at 15 cm in front of a concave mirror.Find its focal length.

• 30cm

• 15cm

• Infinity

• None of the above

Where should an object be placed in front of a convex lens to get a real image of the size of the object?

• At infinity

• At twice the focal length

• At principal focus of the lens

• None