The image of an object formed by a plane mirror is
- (a)erect, real and larger.
- (b)erect, virtual and same size.
- (c)inverted, virtual and same size.
- (d)inverted, real and smaller.
Answer
Why
Correct — B, erect, virtual and same size. A plane mirror forms an image that is virtual — the reflected rays only appear to come from behind the mirror and never actually meet, so it cannot be caught on a screen. The image is erect (the same way up as the object) and exactly the same size as the object. It is also laterally inverted (left and right are swapped) and lies as far behind the mirror as the object is in front of it.
Why the others are wrong
- (a)erect, real and larger. — A plane mirror image is neither real nor magnified; it is virtual and the same size as the object.
- (c)inverted, virtual and same size. — The image is erect, not inverted; a plane mirror reverses left and right (lateral inversion) but does not turn the image upside down.
- (d)inverted, real and smaller. — Wrong on all three counts — the image is erect, virtual and the same size, not inverted, real or smaller.
Concept
A plane (flat) mirror produces an image with fixed characteristics: it is virtual, erect, the same size as the object, laterally inverted, and formed as far behind the mirror as the object is in front. Because the reflected rays diverge and only appear to originate from behind the mirror, the image cannot be projected onto a screen.
The wording tests three properties at once. 'Virtual' and 'same size' rule out any option calling the image real, larger or smaller. 'Erect' rules out 'inverted' — a common trap, since a plane mirror reverses left–right (lateral inversion) but does not flip top–bottom, so the image still stands upright.
Key facts
- A plane mirror image is virtual — it cannot be formed on a screen.
- It is erect (upright) and exactly the same size as the object.
- It is laterally inverted: left and right are interchanged.
- The image distance behind the mirror equals the object distance in front.
Study next
Common traps
- Confusing lateral inversion (left–right) with vertical inversion, and calling the image 'inverted'.
- Thinking a plane mirror image is real because it looks solid — it is virtual and cannot be caught on a screen.
Asked as which set of properties describes a plane mirror image, testing the virtual, erect and same-size characteristics together.
Related PYQs
The image we see in a plane mirror is
- (a) real and thus can be photographed.
- (b) virtual and nearer than the object.
- (c) virtual and is laterally inverted.
- (d) real but cannot be photographed.
Answer(c) virtual and is laterally inverted.
The same plane-mirror image properties: the image is virtual and laterally inverted — the very features (virtual, erect, same size) that make option (B) correct here.
Practice
- practice — not a real PYQ
The image formed by a plane mirror is placed
- (a)in front of the mirror at the same distance as the object
- (b)behind the mirror at the same distance as the object
- (c)at the surface of the mirror
- (d)at infinity
Answer(b) behind the mirror at the same distance as the object — image distance equals object distance. - practice — not a real PYQ
The type of inversion produced by a plane mirror is
- (a)vertical inversion
- (b)lateral inversion
- (c)both vertical and lateral inversion
- (d)no inversion at all
Answer(b) lateral inversion — left and right are interchanged while the image stays upright.