Question

Which of the following forms a virtual and erect image of the same size for all positions of the object?
A. Convex lens
B. Plane mirror
C. Convex mirror
D. Concave mirror

Answer 1

Hint: Plane mirrors are used in our everyday life since they can form virtual and erect images with the same size. All other lenses and mirrors are used for various other applications. Since they can form virtual and real images at specific distances.

Complete step by step answer:
For a convex lens; The object’s position with respect to the focal length (F) determines the image is real or virtual form.
If an object is placed beyond 2F, it will make a real, inverted and size reduced image.
If the object is placed at 2F, then the image will be real, inverted and the same size.
If an object is placed between F and 2F, it will make a real, inverted and enlarged image.
If the object is placed between F and mirror, it will make a virtual, upright and enlarged image.

Concave mirror: It is known as a converging mirror. The image formed by a concave mirror can be real or virtual. They can also form small or large images.
If the object is at infinity, the image will be real and smaller than the object.
If the object is placed at centre of curvature and focus, the image will become real with same size
If the object is placed at between the focus and pole, a virtual and erect image will form.

Convex mirror: It is known as a diverging mirror. Virtual, erect and size reduced images are formed with convex lenses.
If the object is at infinity, the image will be virtual, erect and too small.
If the object is placed between the infinity and the pole, the image will be small, virtual and erect.
A plane mirror can always form virtual, erect with the same size at all the positions of the object placed. That’s why we are using plane mirrors in beauty parlour and household activities. So, the correct option is B.
The image formation in the plane mirror is shown here. Dashed lines are representing the virtual image position. As we discussed earlier, we are getting virtual, erect and same sized images from the plane mirror.

Note: Concave mirrors are mainly used in automobile headlamps, torch, electronic microscopes and astronomical telescopes. Convex mirrors are used in the side view and rear-view mirror of a vehicle. They are also used in the corners of the road to avoid accidents. Since they provide a wide observation. Convex lenses are used in camera, magnifying glasses, microscope etc.