Which one of the following is not true about the image formed by a plane mirror?
- A.It is of the same size as the subject.
- B.It is laterally inverted.
- C.It is real image.
- D.It is formed as far behind the mirror as the object is in front.
Correct answer
Explanation
The correct answer is C, It is real image. A plane mirror always forms a virtual image, one that cannot be caught on a screen, so calling it real is the false statement.
Light rays from an object reflect off a plane mirror and diverge. They never actually meet behind the mirror; they only appear to come from a point behind it, and that is why the image is virtual and erect. The other properties follow from the laws of reflection: the image is the same size as the object, it lies as far behind the mirror as the object is in front of it, and it is laterally inverted, so the right hand appears as the left. This is why AMBULANCE is written in mirror letters on the front of the vehicle.
A is wrong: the image really is the same size, so the statement is true.
B is wrong: lateral inversion is a true property of a plane mirror image.
D is wrong: equal object and image distances are true for a plane mirror.
Exam tip: plane mirror image = virtual, erect, same size, laterally inverted, same distance behind; to see your full height you need a mirror half your height.
Practice Questions
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