A rigid bar of mass 15 kg is supported symmetrically by three wires each 2.0 m long. Those at each end are of copper and the middle one is of iron. Determine the ratios of their diameters if each is to have the same tension.

Two copper wires, one of length 1 m and the other of length 9 m, are found to have the same resistance. Their diameters are in the ratio

A string of mass 2.50 kg is under a tension of 200 N. The length of the stretched string is 20.0 m. If the transverse jerk is struck at one end of the string, how long does the disturbance take to reach the other end?

A body of mass 0.8 kg is whirled uniformlyt at the end of a string 2 m long.If teh string makes 3 revolutins in 1.5 sec,calculate the tension in the string.

A letter .A. consists of a uniform wire of resisrtance .A. one ohm per cm. The sides of the letter are each 20 cm long and crosspiece in the middle is 10cm long, while the apex angle is 60^@ . Find the resistance of the letter between two ends of the legs A. and E as shown in figure given below.

Two small spheres each of mass 10 mg are suspended from a poimt by threads 0.5 m long. They are equally charged and repel each other to a distance of 0.28 m. If g = 10 ms^-2 , what is the charge on each ?

Two long parallel wires are 0.4 m apart in air and carry currents of 5 A and 12 A respectively. Calculate the force on each metre of the wire, fi the currents are in the same direction .

A straight horizontal conducting rod of length 0.45 m and mass 60 g is suspended by two vertical wires at its ends. A current of 5.0 A is set up in the rod through the wires. What will be the total tension in the wires if the direction of current is reversed keeping the magnetic field same as before? (Ignore the mass of the wires.) g = 9.8 m s^-2 .

A 5.0 cm long needle is placed vertically at a distance 20 cm in front of a double convex lens made of a material of refractive index 1.5 having radii of curvature as 10 cm of each surface. Find theheight of image formed.