1.

Convex lens of focal length A and concave lens of focal length B are kept in contact, then the effective focal length of system is .......

Answer»

A+B
A-B
`(AB)/(A+B)`
`(AB)/(B-A)`

SOLUTION :Effective FOCAL length of two lenses kept in CONTACT,
`1/f=(1)/(f_1)+(1)/(f_2)`
`=1/A+(1)/(-B)`
`(-B+A)/(-AB)`
`therefore-((A-B)/(AB))`
`thereforef=(AB)/(B-A)`


Discussion

No Comment Found

Related InterviewSolutions