Class 12th

The relative permeability of iron is 5500. What is its magnetic susceptibility?

Three long wires, carrying current 10 A, 20 A and 30 A are placed parallel to each other as shown. Point P and Q are in midway of wires. What is ratio of magnetic field at P to the Q?

Two identical cells connected in series send 10 A  current through a 5 W resistor. When they are connected in parallel, they send 8 A current through same resistance. What is internal resistance of each cell?

In the shown circuit, current through 4 Ω resistor is

A parallel plate capacitor is charged and then charging battery is disconnected. If the plates are now pulled apart with insulated handles

An ideal engine whose efficiency is 40%, receives heat at 500 K. If required efficiency is 50%, then intake temperature for the same exhaust temperature is

Choose the correct statement.

In a thermodynamic process, pressure of fixed mass of a gas is changed in such a manner that the gas releases 20 J of heat and 8 J of work is done on the gas. If initial internal energy of the gas was 40 J, what will be final internal energy?

Two rain drops reach earth from clouds with different terminal velocities having ratio 9 : 4. Then the ratio of their volumes is

If work done in increasing the size of rectangular soap film with dimensions 8 cm * 3.75 cm to 10 cm * 6 cm is 2 * 10^–4 J. The surface tension of film in newton per meter is