Question

a thin convex lens of focal lenght 30cm is placed in front of a plane mirror. an object is placed at a distance x from the lens so that its first al image coincide itself . then the value of x is

1. 15cm
2.30cm
3.60cm
insufficient data​

Answer 1

Explanation:

Given that, a point object is placed at a distance of 30 cm from a convex mirror of focal length = f = 30 cm.

We have to calculate the distance of the image formed.

Since, we know,

Image distance = f / 2 , behind the mirror

So, 

Image distance = 30 / 2

Image distance = 15 cm , behind the mirror

Hence, option (D) is correct.

Hopefully it helps. Thanks 

.so your answer is 1) 15

###sakshi

Answer 2

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