At which angle (in degrees) does the instantaneous value of a sinusoidal alternating current match its root mean square (r.m.s.) value?

Explanation

For a sinusoidal AC current, the instantaneous current i = I₀ sin(θ), where I₀ is the peak current. The r.m.s. value is I₀/√2. Setting sin(θ) = 1/√2 gives θ = 45°, which is the angle where the instantaneous current equals the r.m.s. current.