Question

Calculate the postion of an image of an object placed 30 centimetre from a concave lens of focal length 15 centimetre

Answer 1

GIVEN:-

• position of the object (u)=-30cm (negative sign is used for concave mirror)

• focal length = -15cm

Using mirror formula , we get

$\boxed{\dfrac{1}{f}=\dfrac{1}{u}+\dfrac{1}{v}}$

${\dfrac{1}{f}-\dfrac{1}{u}=\dfrac{1}{v}$

${\dfrac{-1}{15}-\dfrac{-1}{30}=\dfrac{1}{v}$

${\dfrac{-1}{15}+\dfrac{1}{30}=\dfrac{1}{v}$

${\dfrac{-2+1}{30}=\dfrac{1}{v}$

${\dfrac{-1}{30}=\dfrac{1}{v}$

v=-30cm

Thus, position of the image formed is 30cm away from the mirror

NATURE :- Real , inverted and same size of the object

$\rule{300}{6}$