question_answer 29)

  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.

Answer:

                  The current drawn from d.c. source will increase. This is because when the coil is stretched and air gaps are created between successive elements of the spiral coil, magnetic flux will leak through the gaps. According to Lenz's law, emf induced must resist the decrease in flux. This can be done when more current is drawn from d.c. source.