In a concave mirror, an object is placed at a distance $d_{1}$ from the focus and the image is formed at a distance $d_{2}$ from the focus. Then the focal length of the mirror is:

\sqrt{d_{1} d_{2}}

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d_{1} d_{2}

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(d_{1} + d_{2}) / 2

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\sqrt{d_{1} / d_{2}}

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Solution

The correct option is C $\sqrt{d_{1} d_{2}}$
Let $f$ be the magnitude of the focal length of the mirror.

Using mirror equation ,

$\frac{1}{v} + \frac{1}{u} = - \frac{1}{f}$

$⟹ \frac{1}{- (d_{1} + f)} + \frac{1}{- (d_{2} + f)} = - \frac{1}{f}$

$⟹ f = \sqrt{d_{1} d_{2}}$

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In a concave mirror, an object is placed at a distance d1 from the focus and the image is formed at a distance d2 from the focus. Then the focal length of the mirror is:

The correct option is C √d1d2Let f be the magnitude of the focal length of the mirror.Using mirror equation ,1v+1u=−1f⟹1−(d1+f)+1−(d2+f)=−1f⟹f=√d1d2

In a concave mirror, an object is placed at a distance $d_{1}$ from the focus and the image is formed at a distance $d_{2}$ from the focus. Then the focal length of the mirror is:

The correct option is C $\sqrt{d_{1} d_{2}}$
Let $f$ be the magnitude of the focal length of the mirror.

Using mirror equation ,

$\frac{1}{v} + \frac{1}{u} = - \frac{1}{f}$

$⟹ \frac{1}{- (d_{1} + f)} + \frac{1}{- (d_{2} + f)} = - \frac{1}{f}$

$⟹ f = \sqrt{d_{1} d_{2}}$