1. A real image is cast by a lens. What can be said about the magnification produced by the lens?
2. A concave mirror forms an upright image of an object placed at 20 cm from it. The size of the image is two times that of the object. Find the position of the image. [3 MARKS]

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Solution

First point : 1 Mark
Problem: 2 Marks

1. A real image is always inverted. Also, magnification is given by height of object : height of the image. As the height of given image is negative, therefore, the magnification is also negative.

2. Given:

$h_{i} = 2 h_{o}$

$u = - 20 c m$

$\frac{h_{i}}{h_{o}} = \frac{- v}{u}$
$\frac{2 (h_{o})}{(h_{o})}$ = $\frac{- v}{- 20}$

$v = 40 c m$

The image is 40 cm from the pole behind the mirror.

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1. A real image is cast by a lens. What can be said about the magnification produced by the lens? 2. A concave mirror forms an upright image of an object placed at 20 cm from it. The size of the image is two times that of the object. Find the position of the image. [3 MARKS]

1. A real image is cast by a lens. What can be said about the magnification produced by the lens?
2. A concave mirror forms an upright image of an object placed at 20 cm from it. The size of the image is two times that of the object. Find the position of the image. [3 MARKS]