If a and b denote the distance of the object and image from the focus of a concave mirror, then fig. Shows the graph of $| b |$ versus $| a |$ . The line y=4x cuts the graph at a point whose abscissa is 20 cm. The curvature radius of the mirror is

100 cm

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80 cm

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40 cm

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20 cm

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Solution

The correct option is B 80 cm
$x = 20 cm$
$y = 4 x = 4 \times 20 = 80 cm$
According to newton’s formula, focal length of the mirror is given by
$f^{2} = x y$
$f^{2} = 80 \times 20$
$f^{2} = 1600$
$f = 40 cm$
Radius of curvature is given by the formula
$r = 2 f$
$r = 2 \times 40$
$r = 80 cm$
The radius of the curvature of the mirror is 80 cm.

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If a and b denote the distance of the object and image from the focus of a concave mirror, then fig. Shows the graph of |b| versus |a|. The line y=4x cuts the graph at a point whose abscissa is 20 cm. The curvature radius of the mirror is

The correct option is B 80 cmx=20 cmy=4x=4×20=80 cmAccording to newton’s formula, focal length of the mirror is given byf2=xyf2=80×20f2=1600f=40 cmRadius of curvature is given by the formular=2fr=2×40r=80 cmThe radius of the curvature of the mirror is 80 cm.

If a and b denote the distance of the object and image from the focus of a concave mirror, then fig. Shows the graph of $| b |$ versus $| a |$ . The line y=4x cuts the graph at a point whose abscissa is 20 cm. The curvature radius of the mirror is