A wire in the form of a tightly wound solenoid is connected to a DC source, and carries a current. If the coil is stretched so that there are gaps between successive elements of the spiral coil, will the current increase or decrease? Explain.
The gaps between successive elements of the spiral coil after the coil is stretched, these gaps will tend to leakage in the magnetic flux in the solenoid. According to Lenz’s law, the e.m.f. is produced in nearby coil which will oppose the increase or decrease in magnetic flux in coil in this case magnetic flux decreases i.e. . Thus, opposes the decrease which mean induced e.m.f. should resists the decrease in magnetic flux. It will happen if and only if the current will increase.
Therefore, on stretching the coil, the current will increase.