Electromagnetic induction concept check: What is the induced voltage across a stationary conductor placed in a stationary magnetic field?

Introduction / Context:
Faraday’s law of electromagnetic induction explains how changing magnetic environments produce electric potentials. This question distinguishes the necessary conditions for an induced voltage from static scenarios where no induction occurs.

Given Data / Assumptions:

• The conductor is stationary.
• The magnetic field is static (unchanging in time and space relative to the conductor).
• No motion or time-varying flux is present.

Concept / Approach:
Faraday’s law states that the induced electromotive force (emf) in a circuit equals the negative time rate of change of magnetic flux linking the circuit: emf = - dΦ/dt. Motional emf requires relative motion v between the conductor and magnetic field: emf = B * l * v (for a straight conductor orthogonal to B and motion). If both the field and conductor are stationary, and flux is constant, dΦ/dt = 0 and v = 0, so the induced voltage is zero.

Step-by-Step Solution:

Verification / Alternative check:
Practical lab confirmation: With a coil or bar held fixed inside a constant magnetic field and no time variation or movement, a voltmeter reads 0 V. Induction readings appear only when the field changes or the conductor moves (e.g., rotating a loop in a generator).

Why Other Options Are Wrong:

• Increased/Decreased: Suggests a nonzero starting value, which does not exist here.
• Reversed in polarity: Polarity reversal occurs when motion direction or field direction flips while emf is nonzero; not applicable in a wholly static case.

Common Pitfalls:

• Assuming any magnetic field automatically induces voltage—induction requires change or motion.
• Confusing static flux presence with flux change.

Final Answer:
zero