Question

in which by a convex lens of focal length is 15cm when the object is placed at a distance of 18cm from the lens determine the size of image formed if size of object is 4cm​

Answer 1

CONVEX LENS

FOCAL LENGTH= +15cm

OBJECT DISTANCE= (-18)cm

we know that :-

$\boxed{\bold{\Large{\sf{\boxed{\dfrac{1}{f}=\dfrac{1}{v}-\dfrac{1}{u}}}}}}$

$\rule{200}{2}$

On applying the formula we get:-

v = 90 cm

also we know from magnification:-

$\dfrac{h_i}{h_o}=\dfrac{v}{u}\\ \\ \\ \\h_i = \dfrac{v*h_o}{u}\\ \\ \\ \\ h_i=\dfrac{90*4}{-18} = -20$

hence,

the size of the image is 20 cm from the pole.

the image is real and inverted and magnified(highly)