Question

PLEASE ANSWER PLEASE...
I CAN'T UNDERSTAND IT??
HOW WE CAN KNOW NATURE OF IMAGE FROM THE QUESTION..? I MEAN IN QUESTION NO 7 IT IS SAYING IT IS CONVEX LENS, SO HOW IT KNOW THAT IT IS CONVEX OR CONCAVE LENS FROM QUESTION PLEASE ANSWER I WILL DEFINITELY MARK U AS BRAINLIST PROMISE​

Answer 1

Answer:

It is easy to identify the type of lens from the question because if in the question it is written that the image formed is on the other side that means the image formed is real so the lens will be convex lens and if in the question it is mentioned that the image formed is on the same side that is the image formed will be virtual and hence the lens will be concave lens as we know that in convex lens there is a special case in which virtual image is formed in that case the in the question it will be mentioned that the image formed is enlarged by following these simple steps you would be able to identify the type of lens by just reading the question.

HOPE IT WILL HELP!!!

Answer 2

Answer:

Explanation:

a) by finding the focal length we can say if it is concave or convex lens.

if focal length is negative it will be concave lens.

if focal length is positive it will be convex lens.

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

$\frac{1}{f} =\frac{1}{90} -\frac{1}{-45}$

$\frac{1}{f} =\frac{1+2}{90}$

$\frac{1}{f} = \frac{3}{90}$

$f= 30 cm$

since focal length is positive it is a convex lens.

b) (i) focal length = 30 cm (as solved above)

c) for lens

$m=-\frac{v}{u}$

$m=-\frac{90}{45}$

$m=-2$