Assertion (A) : Work done in moving a charge around a closed path, in an electric field is always zero.

Reason (R) : Electrostatic force is a conservative force.

Assertion (A) : In Young's double slit experiment all fringes are of equal width.

Reason (R) : The fringe width depends upon wavelength of light $$(\lambda)$$ used, distance of screen from plane of slits (D) and slits separation (d).

Briefly explain why and how a galvanometer is converted into an ammeter.

(a) How are infrared waves produced? Why are these waves referred to as heat waves? Give any two uses of infrared waves.

OR

(b) How are X-rays produced? Give any two uses of these.