Question

The magnification produced by a concave mirror

A) is always more than one

B) is always less than one

C) is always equal to one

D) maybe less than or greater than one.

Answer 1

Hint: The ratio of the height of the image to the height of the object is termed as Magnification. The concave mirrors produce virtual or real, erect or inverted, diminished or the same size depending on the position of the object placed.

Complete step by step answer:

The expression for magnification is given as,

$m = \dfrac{h'}{{h}}$

Where $h$ is the height of the object and $h'$ is the height of the image. And $h$, $h'$ can have negative or positive according to the Cartesian sign convention.

When the image and the object have the same size the magnification will be one. If the image is diminished the magnification will be greater than one. If the image is enlarged the magnification will be less than one. The negative sign indicates that the image is real and the positive indicates that the image is virtual.

Position Of Object	Position Of Image	Image Type	Magnification
Infinity	Focus (F)	Real and Point	0
Between Infinity and Center Of Curvature (C)	Between Focus (F) and Center Of Curvature (C)	Real and Inverted, Smaller than object	Less than 1
On Center Of Curvature (C)	At Center Of Curvature (C)	Real and Inverted, Equal to object	Equal to 1
Between Center Of Curvature (C) and Focus (F)	Between Infinity and Center Of Curvature (C)	Real and Inverted, Bigger than object	Greater than 1
On Focus (F)	At Infinity	Real and Inverted, Bigger than object	Greater than 1
Between Focus (F) and Pole (O)	Back Side of Mirror	Virtual and Erect Image, Bigger than object	Greater than 1

Note:

In a concave mirror, when the distance of the object is less than the focal length, the magnification will be greater than one. When the distance of the object is greater than the focal length, then the magnification is less than one.