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31. Alternating Current

Alternating Voltages and Currents

31. Alternating Current

Alternating Voltages and Currents

Multiple Choice
An AC source produces an alternating current in a circuit with the function $i\left(t\right)=\left(1.5A\right)\cos\left\lbrack\left(250s^{-1}\right)t\right\rbrack$ . What is the frequency of the source? What is the maximum current in the circuit?
Multiple Choice
The current in an AC circuit takes 0.02 s to change direction. What is the angular frequency of the AC source?
Multiple Choice
An AC emf source is given by $ε = (170 V) \cos {2 π (60 Hz) t}$ . What is the instantaneous emf of this source at $t = 97 ms$ ?
Multiple Choice
An AC emf source is given by $ℰ = (170 V) \cos (2 π (60 Hz) t)$ . What is the instantaneous emf of this source at $t = 97 ms$ ?
Multiple Choice
If $V_{rms} = 120 V$ for a certain 60 Hz outlet, what is the peak voltage across the outlet?
Open Question
A sinusoidal current i = I cosωt has an rms value I_rms = 2.10 A. (a) What is the current amplitude?