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.
Correct — C, virtual and is laterally inverted. A plane mirror forms an image by reflecting diverging rays; the rays only appear to come from behind the mirror, so no real image is formed on a screen — the image is virtual. It is also laterally inverted (left and right are swapped, which is why 'AMBULANCE' is printed mirror-reversed on the front of vehicles). The image is erect, the same size as the object, and lies as far behind the mirror as the object is in front.
- (a)real and thus can be photographed. — A plane-mirror image is virtual, not real — rays do not actually meet behind the mirror, so it cannot be caught on a screen placed there.
- (b)virtual and nearer than the object. — The 'virtual' part is right, but the image is not nearer — it lies exactly as far behind the mirror as the object is in front, and it is the same size, not diminished.
- (d)real but cannot be photographed. — It is virtual, not real; and a camera can by focusing as if the object were behind the mirror, so the reasoning is doubly wrong.
When light from an object strikes a plane mirror it reflects according to the law of reflection (angle of incidence = angle of reflection). The reflected rays diverge and only appear to originate from a point behind the mirror. That apparent meeting point gives a virtual, erect image of the same size, located as far behind the mirror as the object is in front, and laterally inverted.
The trap is the word 'real'. Students confuse being able to being real. 'Real' has a precise meaning can fall on a screen. A plane mirror never does this, so options calling the image 'real' are automatically wrong, leaving the virtual + laterally inverted description.
- A plane-mirror image is virtual, erect and the same size as the object.
- The image is as far behind the mirror as the object is in front of it.
- The image is laterally inverted — left and right appear swapped.
- A virtual image cannot be caught on a screen but can still be photographed by a suitably focused camera.
- Calling a mirror image 'real' because it looks sharp — real means rays actually converge on a screen.
- Thinking the image is nearer or smaller — it is the same size and equidistant behind the mirror.
Asked as the nature of a plane-mirror image (virtual, erect, laterally inverted, same size) or through the classic 'AMBULANCE' lateral-inversion example.
No directly related past PYQ was found.
- practice — not a real PYQ
An object is placed 15 cm in front of a plane mirror. The distance between the object and its image is
- (a)15 cm
- (b)30 cm
- (c)7.5 cm
- (d)45 cm
Answer(b) 30 cm — the image is 15 cm behind the mirror, so object and image are 15 + 15 = 30 cm apart.
- practice — not a real PYQ
The image formed by a plane mirror is always
- (a)real and inverted
- (b)virtual and erect
- (c)real and magnified
- (d)virtual and diminished
Answer(b) virtual and erect — and the same size as the object.