For a convex lens when the object is at 2F₁, then image is formed at :

1. F₂
2. 2F₂
3. beyond 2F₂
4. infinity

A concave lens is used in :

1. in slide projector
2. as magnifying glass
3. as burning glass
4. in Galilean telescope

A blue light beam forms an image of an object using a convex lens. If the blue light is replaced by red light, how will the image change?

1. Image will shift closer to the lens and become smaller.
2. Image will shift farther from the lens and become larger.
3. The position of the image will not change, only its brightness changes.
4. No change will be seen

Assertion (A): The focal length of a lens does not change when red light is replaced by blue light.

Reason (R): The focal length of a lens depends on the refractive index of material of lens.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true and R is not the correct explanation of A.
3. assertion is false but reason is true.
4. assertion is true but reason is false.