A metallic disc of radius a rotates with angular speed ω inside a long solenoid of N turns and length ℓ. The disc and solenoid form a circuit of total resistance R. Select the correct statements.

Select all that apply

• Option A

  With solenoid current i, disc emf between P and Q is µ₀Niωa²/(2ℓ).

• Option B

  Depending on ω, the solenoid current can increase or decrease with time.

• Option C

  The minimum ω for increasing current is ℓR/(2µ₀Na²).

• Option D

  The minimum ω for increasing current is 2ℓR/(µ₀Na²).