Question

Q8. A converging lens has a focal length of 15cm. An object is placed 60cm from the lens. Determine the

image distance and size.​

Answer 1

Given:

• $\bold{It~ is ~a~ converging~ lens~ that ~is ~convex ~lens.}$

Solution:

$\sf{Focal ~length , f = 15 cm}$

$\sf{Object ~distance , u = - 60 cm}$

$\sf{Image ~distance, v = v}$

$\sf{Lens~ formula:}$

⠀⠀⠀⠀⠀$\longrightarrow$$\tt{\frac{1}{v} - \frac{1}{u} = \frac{1}{f}}$

⠀⠀⠀⠀⠀${↪}$$\tt{\frac{1}{v} - (\frac{1}{-60})= \frac{1}{15}}$

⠀⠀⠀⠀⠀⠀⠀${↪}$$\tt{\frac{1}{v}+\frac{1}{60} =\frac{1}{15}}$

⠀⠀⠀⠀⠀⠀⠀⠀⠀${↪}$$\tt{\frac{1}{v}= \frac{1}{15}+\frac{1}{60}}$

⠀⠀⠀⠀⠀${↪}$$\tt{\frac{1}{v}=\frac{ ( 4 +1)}{60}}$

⠀⠀⠀⠀⠀⠀⠀⠀${↪}$$\tt{\frac{1}{v} =\frac{5}{60}}$

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀${↪}$$\tt{V = 12 cm}$

${:⇒}$ The determined image and size is 12cm