Assertion `:` The focal length of the mirrorr is `f` and distance of the object from the focus is `u` , the magnification of the mirror is `f//u`.
Reason : Magnification `=("Size of the image")/("Size of object" )`

Options

A. Both A and R are true and R is the correct explanation of A
B. Both A and R are true but R is NOT the correct explanation of A
C. A is true but R is false
D. A is false and R is True

Answer

A

Explanation

`f + x`
Using mirror formula
`1//v + 1//u = 1//f`
or `1//v = 1//(f + x) = -1//f`
`therefore v = -f(f+x)//x`
Magnification (m) = size of image f size of object = `v//u`
`|m| = (f(f + x))/(x) xx 1/(f + x) = f//x`
So the assertion and reason both are true and the reason properly explains the assertion.