AC Generator: Frequency and Peak EMF Determine Lamp Flashing and Brightness

Steps:

• Lamp flashes at the AC frequency, which equals the coil's rotation frequency.
• Initial rotation gives 2 flashes/second, so frequency f = 2 Hz.
• Halving rotation rate halves f to 1 Hz, so 1 flash/second.
• Peak voltage (and thus maximum brightness) is V_peak = N B A ω, where ω halves, reducing V_peak and brightness.

Why A is correct:

• Halving rotation rate halves frequency (1 flash/second) and peak emf (V_peak ∝ ω), decreasing maximum brightness per Faraday's law.

Why the others are wrong:

• B: Frequency halves (not 4 Hz); brightness decreases.
• C: Maximum brightness decreases with halved peak emf.
• D: Frequency halves (not 4 Hz); ignores emf reduction.

Final answer: A