Two objects A and B when placed one after another infront of a concave mirror of focal length 10 cm from images of same size. Size of object A is four times that of B. If object A is placed at a distance of 50 cm from the mirror, what should be the distance of B from the mirror

10 cm

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20 cm

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30 cm

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40 cm

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Solution

The correct option is B 20 cm
By using $\frac{I}{O} = \frac{f}{f - u} \Rightarrow \frac{I_{A}}{I_{B}} = \frac{f - u_{B}}{f - u_{A}} \Rightarrow \frac{1}{1} \times \frac{1}{4} = \frac{- 10 - u_{B}}{- 10 - (- 50)} \Rightarrow u_{B} = - 20 c m$ .

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Two objects A and B when placed one after another infront of a concave mirror of focal length 10 cm form images of same size. Size of object A is four times that of B. If object A is placed at a distance of 50 cm from the mirror, what should be the distance of B from the mirror?

Q. Two objects A and B when placed in front of a concave mirror, give images of equal size. The focal length of the concave mirror is

7.5 c m

and size of object A is three times the size of object B. The distance of B from the mirror, if A is placed

30 c m

from the mirror, is:

Q. Two objects A and B when placed in front of a concave mirror of focal length

7.5 c m

, give images of equal size. If A is three times the size of B and is placed

30 c m

from the mirror, what is the distance of B from the mirror?

At what distance from a concave mirror of focal length 25 cm should an object be placed so that the size of image is equal to size of the object.

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Two objects A and B when placed one after another infront of a concave mirror of focal length 10 cm from images of same size. Size of object A is four times that of B. If object A is placed at a distance of 50 cm from the mirror, what should be the distance of B from the mirror

The correct option is B 20 cmBy using IO=ff−u⇒IAIB=f−uBf−uA⇒11×14=−10−uB−10−(−50)⇒uB=−20cm.

The correct option is B 20 cm
By using $\frac{I}{O} = \frac{f}{f - u} \Rightarrow \frac{I_{A}}{I_{B}} = \frac{f - u_{B}}{f - u_{A}} \Rightarrow \frac{1}{1} \times \frac{1}{4} = \frac{- 10 - u_{B}}{- 10 - (- 50)} \Rightarrow u_{B} = - 20 c m$ .