Question

An object is 5 cm in front of a convex lens of focal length 7.5 cm.What is the position and magnification of the image​

Answer 1

Answer:

In this question

$f = + 7.5cm \: \: \: \: \: \: \: ( \because \: lens \: is \: convex) \\ \\ u = - 5cm \\ \\ v = ?$

Using Lens Formula

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

$\dfrac{1}{v} = \dfrac{1}{f} + \dfrac{1}{u } \\ \\ = \dfrac{1}{7.5} + \dfrac{1}{ - 5} \\ \\ = \dfrac{1}{7.5 } - \dfrac{1}{5} \\ \\ = \dfrac{ - 1}{15} \\ \\ \implies\red{ \boxed {\boxed{ v = - 15cm}}}\:$

Negative sign shows that image is at the the left side of the lens.

$magnification = m = \dfrac{v}{u} \\ \\ = \dfrac{ - 15}{ - 5} \\ \\ \implies \red{ \boxed {\boxed{ m = 3}}}$

Answer 2

Answer:

v = -15cm

m = 3

Explanation:

See the attachment

Hope it helps you