Describe schematically the equipotential surfaces corresponding to a. a constant electric field in the z-direction. b. a field that uniformly increases in magnitude but remains in a constant (say,z) direction. c. a single positive charge at the origin, and d. a uniform grid consisting of long equally spaced parallel charged wires in a plane.

Two wires of equal cross section but one made of steel and the other of copper, are joined end to end. When the combination is kept under tension, the elongations in the two wires are found to be equal. Find the ratio of the lengths of the two wires. Young modulus of steel =2.0xx10^11Nm^-2 and that of copper =1.1xx10^11Nm^-2

A sphere of charge +Q is fixed. A smaller sphere of charge +q is placed near the larger sphere and releasted from rest. The samll sphere will move away from large sphere with (a) decreasing velocity & decreasing acceleration. (b) decreasing velocity & decreasing acceleration. (c) decerasing velocity & constant acceleration. (d) increasing velocity & decreasing acceleration. (e) increasing velocity & decreasing acceleration. Which of the above statement is correct Explain.

Shows a smooth pair of thick metallic rails connected across a battery of emf epsilon having a negligible internal resistance. A wire ab of length l and resistance r can slide smoothly on the rails. The entire system lien in a horizontal plane and is immersed in a uniform vertical magnetic field B. At an instant t, the wire is given a small velocity v towards right. (a) find the current in it at this instant. What is the direction of the current? (b) What is the force acting on the wire at this instant? (c) Show that after some time the wire ab will slide with a constant velocity. Find this velocity.

Determine the poissons ratio of the material of a wire whose volume remains constant under an external normal stress.

The ratio of strees and strain of a wire is 3:2. Find the co-efficient of elasticity. Express the result in SI unit system.

Two wire A & B are of the same metal and are of same length have area of cross section in the ratio of 2:1 If the same potential difference is applied across each wire. What will be the ratio of the current flowing through the wires A & B ?

Shown a metallic square frame of edga a in a vertical plane. A uniform magnetic field B exists in the space in a directon perpendicular to the plane of the figure. Two boys pull the opposite corners of the square ot deform it into a rhombus. They start pulling the corners t t=0 and sisplace the corners at a uniform speed u. (a) find the induced emf in the frame at the instant when the angles at these corners reduce to 60^@ . (b) find the induced current in the frame at this instatnt if the total resistance of the frame is R. (c) Find the total charge which flows through a side of the frame by the time the square is deformed into a straight line.

Determine the poisson's ratio of the material of a wire whose volume remains constant under an external normal stress.