Question

Assertion: If a current is flowing through a machine of iron, eddy currents are produced.

Reason: The change in magnetic flux through an area causes eddy current

• A. Both A and R are true and R is the correct explanation
• B. A is true but R is false
• C. Both A and R are false
• D. Both A and R are true but R is not the correct explanation

Answer 1

The correct option is A

Both A and R are true and R is the correct explanation

Explanation for the assertion: If a current is flowing through a machine of iron, eddy currents are produced.

1. Current flowing through a machine of iron causes an eddy current.
2. Eddy currents are loops of electrical current in a conductor carrying changing electric current.
3. current-induced as a change in magnetic flux basically causes eddy currents and the current flowing through a machine of iron causes eddy current.

Explanation for the reason: Change in magnetic flux through an area causes eddy currents.

1. We all know about Faraday’s law of electromagnetic induction. It consists of two laws.
2. The first law states that whenever an electric current flows through a conductor, a magnetic field is produced, and conversely a changing magnetic field generates an electric current.
3. The second law states that the change in magnetic flux with time produces an electromotive force.
   $\mathrm{\Phi }=B.A=BA\cos \theta$
4. Where $\mathrm{\Phi }$ is the flux produced, $B$ is the magnetic field, $A$ is the surface area and $\theta$ is the angle between the magnetic field lines and normal to surface area.
5. Also,$\epsilon =-N{\displaystyle \frac{d\mathrm{\Phi }}{dt}}$Where $\mathrm{\Phi }$ is the flux produced, $t$ is the time, $N$is the number of turns in the coil and $\epsilon$ is the electromotive force or the EMF produced.
   In this case, the changing current generates a magnetic field. As the parts are made of iron, the flux will be different at different parts of the machine and so EMF will be produced. This EMF can produce an eddy current which will produce heat and hence loss of energy in the form of heat.

Hence, Aasertion and reason are correct and the reason is the correct explanation of assertion.

Hence, option A is the correct answer.