Exercise

Find the focus and position of the lens by drawing a ray diagram using the position of object $A$ and the image $A\text{'}$ in the given diagram.

$10 \mathrm{V}$ battery is connected in an electric circuit. Between A and B points $20 \mathrm{\Omega }$ and $30 \mathrm{\Omega }$  resistors are connected to get least resistance in the circuit. Find the resultant resistance between A and B and find current in the circuit.

The focal length of a symmetrical converging lens is equal to the radius of curvature. Then the refractive index is

If $-D$ power lens is used for the correction of the eye defect, then the lens used is

An object is placed in front of the concave mirror, then object distance, image distance and magnifications as per sign conventions i.e., $-u,+v,+m$ for the following one diagram is

Correct ray diagram from the following is

Correct ray diagram from the following is

Image formed when we read the paper by using magnifying glass is