Mix Examples - Magnetic Effects of Electric Current Questions in English

(A) According to Faraday's Law of Electromagnetic Induction,the induced $EMF$ $(\varepsilon)$ in a coil is given by the formula: $\varepsilon = -N \frac{d\Phi_B}{dt}$.
Here,$N$ is the number of turns in the coil and $\frac{d\Phi_B}{dt}$ is the rate of change of magnetic flux.
The magnetic flux $\Phi_B$ depends on the magnetic field strength and the area of the coil,which is influenced by the speed of the magnet and the number of turns.
The shape of the coil does not directly determine the magnitude of the induced $EMF$ in this context,as the $EMF$ depends on the total flux linkage and the rate of change,not the geometric configuration of the wire itself.

(B) In an electric generator,a split ring (commutator) is used to reverse the direction of the current in the coil after every half rotation,which ensures that the output current flows in a single direction $(DC)$.
If a full circular ring (slip ring) is used instead of a split ring,the direction of the induced current in the coil reverses after every half rotation without being rectified.
Consequently,the current flowing through the external circuit changes its direction periodically,resulting in the production of alternating current $(AC)$.

(D) In most power plants (such as thermal,hydroelectric,or nuclear power plants),electricity is generated by rotating a turbine connected to a generator. The generator works on the principle of electromagnetic induction,where a changing magnetic field induces an electromotive force $(EMF)$ in a coil,thereby producing electricity.