Question

1. What is the focal length of the convex lens? Give reason to justify your
answer.
2. Write the serial number of the observation which is not correct. On whal
basis have you arrived at this conclusion?
​

Answer 1

Explanation:

I) Focal Length= 2Ocm

Observing s no.3;

We find that u and v are same that corresponds to case when object is at 2f(I) position of convex mirror and image is formed at 2f(II).

II) Sno.6 is not correct.

As when the object is placed before the focal length (between optical centre and focal length);

the image is formed beyond 2f(I);

which means v must be negative.

but in sno.6; v is positive

thus sno.6 is wrong