Induced emfs are best explained using

Step 1: Analyze the question The question asks which law best explains how an emf is induced, for example when a magnet moves near a coil.

Step 2: Explain the concept Look at what each law covers:

• Ohm's law: relates voltage, current and resistance (V = IR). It has nothing to do with inducing an emf.
• Faraday's law: states that the magnitude of the induced emf is directly proportional to the rate of change of magnetic flux linkage:

E = −N (ΔΦ / Δt)

This tells you how much emf is induced and why it appears. It is the main law of electromagnetic induction.

• Coulomb's law: gives the force between two point charges (F = kq₁q₂/r²). It belongs to electrostatics.
• Lenz's law: gives the direction of the induced emf or current, which always opposes the change that produced it. It explains the negative sign in Faraday's equation, but it does not explain the induction itself or its size.

Step 3: Solution Induced emf depends on how fast the magnetic flux changes, and this is exactly what Faraday's law describes. Lenz's law only adds the direction, so it is a supporting rule. Faraday's law is the one that best explains induced emfs.

Step 4: Answer The correct option is B. Faraday's law.

Step 5: Exam tip

• Faraday = "How much?" (magnitude of induced emf)
• Lenz = "Which way?" (direction, from the negative sign)

If a question mentions magnitude, rate of change of flux or number of turns, think Faraday. If it mentions direction or opposition to change, think Lenz.