If the magnification of a body of size $1\, m$ is $2$,what is the size of the image (in $m$)?

What is the power of a convex lens with a focal length of $20 \text{ cm}$?

$A$ convex mirror can be used to see a large image of a small object.

$(a)$ State the relation between object distance,image distance and the focal length of a spherical mirror.
$(b)$ Draw a ray diagram to show the image formed by a concave mirror when an object is placed between the pole and focus of the mirror.
$(c)$ $A$ concave mirror of focal length $15\, cm$ forms an image of an object kept at a distance of $10\, cm$ from the mirror. Find the position,nature and size of the image formed by it.

What is meant by a lateral shift?

What happens when a light ray incident normally on the surface of a glass slab enters from air into the glass?