Question

An object is placed at a distance u from a concave mirror and its real image is formed on the screen placed at distance v from the mirror. If f is the focal length of the mirror, then the graph between `1/"v"` versus `1/"u"` is (magnitude only).

Options

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Answer 1

Explanation:

`"Since"  1/"f" = 1/"v" + 1/"u"`

`1/"v" = -1/"u" + 1/"f"`

Using the sign conventions,

`1/((- "v")) = -1/((- "u")) + 1/((-"f"))`

`1/"v" = -1/"u" + 1/"f"`

Comparing this equation with

y = mx + c

Slope= m = tan `theta` = - 1

`theta`= 135° or -45° and intercept

`"c" = +1/"f"`

This is best depicted by graph (B).