Name three liquids which when tested in the manner shown in figure may cause the magnetic needle to deflect.

Can you name the test shown in the figure ?

Some magnetic flux is changed from a coil of resistance 10Omega . As a result an induced current is developed in it, which varies with time as shown in figure. What is the magnitude of change in flux through the coil ?

When the free ends of a tester are dipped into a solution, the magnetic needle shows deflection. Can you explain the reason?

When a mass M hangs from a spring of length l, it stretches the spring by a distance x. Now the spring is cut in two parts of length l/3 and 2l/3, and the two springs thus formed are connected to a straight rod of mass M which is horizontal in the configuration shown in figure. Find the stretch in each of the spring.