Question

An object is placed at a distance 2 f from a convex lens of focal length f. The size of image formed is ____ that of the object.
a) highly diminished
b) magnified
c) same as
d) diminished
​

Answer 1

Answer:

$\boxed{\mathfrak{(c) \ same \ as}}$

Explanation:

Object distance (u) = -2f

Focal length (f) = f

Magnification in terms of u and f is given as:

$\boxed{ \bold{m = \dfrac{f}{u + f} }}$

By substituting values we get:

$\rm \implies m = \dfrac{f}{ - 2f + f} \\ \\ \rm \implies m = - \cancel{\dfrac{f}{f} } \\ \\ \rm \implies m = - 1$

Magnification is 1 that means that image formed is same size as object and the negative magnification denotes that image formed is inverted.

Answer 2

Explanation:

Answer of Two wires of the same material and same length have radii 1 mm and 2 mm respectively. Compare i their resistances ii their ...