1.

Two convex lenses 1 and 2 having focal lengths 25 cm and 30 cm are kept in contact such that they have the same principle axis, focal length of this combination motion is ......

Answer»

1.36
13.6
31.6
61.3

Solution :
`1/f=(1)/(f_1)+(1)/(f_2)`
`THEREFORE f= (f_1f_2)/(f_1+f_2)`
`=((25)(30))/(25+30)=(750)/(55)" "thereforef=13.6`


Discussion

No Comment Found

Related InterviewSolutions