Image of an Object Placed at Infinity

When an object is placed at infinity, the rays of light coming from the object are considered to be parallel to each other. This occurs when the object is very far away from the optical system, such as a lens or a mirror.

In order for the image of the object to be highly diminished and point sized, the rays of light after reflection or refraction must converge to a single point. Let's analyze each of the given options to determine which one satisfies this condition.

a) Concave Mirror Only

A concave mirror is a converging mirror, meaning it focuses incoming light rays to a single point called the focal point. However, when an object is placed at infinity, the rays of light are already parallel, so a concave mirror cannot further converge them to a single point. Therefore, the image formed by a concave mirror when the object is at infinity is not highly diminished and point sized.

b) Convex Mirror Only

A convex mirror is a diverging mirror, meaning it spreads out incoming light rays. When an object is placed at infinity, the convex mirror will still diverge the already parallel rays of light. As a result, the image formed by a convex mirror when the object is at infinity is not highly diminished and point sized.

c) Convex Lens Only

A convex lens is a converging lens, meaning it converges incoming light rays to a single point. When an object is placed at infinity, the convex lens can further converge the parallel rays of light to a single point, forming a highly diminished and point-sized image.

d) Convex Mirror, Convex Mirror, Concave Lens, and Convex Lens

None of these options satisfy the condition for creating a highly diminished and point-sized image when the object is placed at infinity. As discussed earlier, convex mirrors and convex lenses cannot achieve this. Additionally, a concave lens is a diverging lens, meaning it spreads out incoming light rays. Therefore, none of these options are correct.

Conclusion

Based on the analysis above, the correct option is d) Convex mirror, convex mirror, concave lens, and convex lens. Only a convex lens is capable of forming a highly diminished and point-sized image when the object is placed at infinity.