Skip to main content
Physics Guru is an online education and competitive examinations preparation portal founded by Manish Verma, an IIT Madras alumnus, providing learning resources for competitive examinations.

The emphasis is on conceptual understanding, analytical thinking and problem solving rather than simply memorising formulas and standard methods.

The objective is to help students understand what they are learning and develop the ability to solve problems they have not seen before.

The following letter may be of general interest:

Respected Sir,

I have a confusion about the topic optics. I am very confused about the sign convention used in solving lens problems or spherical mirror problems. Please aware me what is the true sign convention to be used.

Thanking you ...

Answer: There are two kinds of sign conventions:

1. Real-Virtual.
2. Co-ordinate.

Both are correct and can be used. However, co-ordinate sign convention is found easy by most and therefore is recommended.