Question

A machine is run such that electrical current is input and as a result rotation is achieved in the rotor. If current is turned off and rotation is forced in the machine.
A) Current is produced.
B) Rotator motion faces resisting force.
C) Machine acts as a generator.
D) All of the above.

Answer 1

According to Lenz's law the induced electromotive force due to the change in magnetic field generates the current to flow from the current and it will create a magnetic pole such that it will oppose the original magnetic field which created the current to flow.

Complete step by step solution:
It is asked in the problem that if the current in the electrical rotor is not supplied and the motor is forced rotation motion then we need to tell what is the correct option for this problem.
When an electrical motor is supplied then the motor rotates and supplies power as output but when the current is turned off and the rotor is forced motion then the current is induced due to electromagnetic induction. The Lenz law says that the induced current will create a magnetic field such that it will oppose the original magnetic field which will oppose the original magnetic field that creates the current to flow. In this process the current is produced, the rotor motion faces resisting force due to the magnetic field produced due flowing current. The machine which produces the electricity can be considered as a generator. The correct option for this problem is option D.

Additional information: The Lenz law has a main application that it helps us to generate the electricity on which every other appliance works. In a steam power plant the water is converted into steam and then is forced into the generator. The generator has a motor having coils and is present inside the stationary magnet so when the coil rotates inside a large stationary magnet then electricity is generated following the Lenz law.

Note: It is very important for students to understand and remember the concept of the Lenz law as it is very important in solving these kinds of problems. The Lenz law states that the change in magnetic field creates current and this current again creates a magnetic field and this magnetic field opposes the original magnetic field which created the current to flow.