Question

a concave lens of focal length 15cm forms an image at 10cm from the lens. how far is the object placed from the lens? and which side​

Answer 1

${\bf{\implies Hola \: mate \: here \: is \: your \: answer}}$

$\boxed{\bf{\green{\longrightarrow Given:}}}$

• Concave lens
• F = -15cm
• v = -10cm

$\boxed{\bf{\red{\longrightarrow Answer}}}$

• Using mirror formula
• $\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$
• $\frac{1}{u} = \frac{1}{ - 10} + \frac{1}{15}$
• $\frac{1}{u} = \frac{ - 5}{150} = \frac{ - 1}{30}$
• $u = - 30cm$
• So Object is in front of the mirror