An alternating current has peak value 5 A and frequency 60 Hz. Starting from zero and increasing sinusoidally, how long will it take to first reach its maximum positive value?
Options

Question

An alternating current has peak value 5 A and frequency 60 Hz. Starting from zero and increasing sinusoidally, how long will it take to first reach its maximum positive value?

G1 Physics · Accepted Answer

Step 1: Write i = I₀ sin(ωt), choosing t = 0 at the zero crossing. Step 2: The first peak occurs when ωt = π/2. Step 3: Angular frequency ω = 2πf = 2π × 60 rad·s⁻¹. Step 4: t = (π/2)/(2πf) = 1/(4f) = 1/(4 × 60) = 1/240 s. Final answer: 1/240 s (Option B).