Question:medium

Which of the following statements is not correct for electromagnetic induction?

Show Hint

The key term in Faraday's Law is "rate of change." Many incorrect statements will omit the "rate" part and just mention the "change" in flux. Always look for the dependence on time (\(d/dt\) or \(\Delta/\Delta t\)).
Updated On: Mar 27, 2026
  • The magnitude of induced emf in a circuit is equal to the time rate of change of magnetic flux through the circuit.
  • The magnitude of induced emf in a circuit is equal to the total change of magnetic flux through the circuit.
  • The induced emf can be increased by increasing the number of turns N of a closed coil.
  • The polarity of induced emf is such that it tends to produce a current which opposes the change in magnetic flux that produced it
Show Solution

The Correct Option is B

Solution and Explanation


Step 1: Concept Identification:
This question assesses understanding of Faraday's Law and Lenz's Law of electromagnetic induction. The objective is to identify the statement that inaccurately represents these laws.

Step 2: Detailed Analysis:
1. Faraday's Law (Correct): The magnitude of the induced electromotive force (EMF) in a circuit is directly proportional to the rate at which the magnetic flux through the circuit changes. Mathematically, this is expressed as \(|\mathcal{E}| = \left|\frac{d\Phi_B}{dt}\right|\). This statement accurately reflects Faraday's Law.
2. Incorrect Statement: This statement posits that the magnitude of the induced EMF equals the total change in magnetic flux (\(|\mathcal{E}| = |\Delta\Phi_B|\)). This is erroneous. The induced EMF is contingent upon the speed of flux change (the rate, \(\Delta\Phi_B / \Delta t\)), not solely the magnitude of the flux change. A substantial flux change occurring slowly will induce a minimal EMF. Therefore, this statement is incorrect.
3. Effect of Coil Turns (Correct): For a coil comprising \(N\) turns, Faraday's Law is formulated as \(|\mathcal{E}| = N \left|\frac{d\Phi_B}{dt}\right|\). The total induced EMF is the aggregate of EMFs in each turn. Consequently, augmenting the number of turns \(N\) directly escalates the total induced EMF. This statement is correct.
4. Lenz's Law (Correct): This statement accurately describes Lenz's Law, which dictates the direction of the induced current and the polarity of the induced EMF. The induced EMF's polarity is such that it generates a current opposing the change in magnetic flux that caused it. This statement is correct.

Step 3: Conclusion:
The question seeks the incorrect statement regarding electromagnetic induction. Statement (2) provides a factually inaccurate representation of this principle.

Was this answer helpful?
0


Questions Asked in CUET (UG) exam