Physics 9702 · AS & A Level · Characteristics of alternating currents
Characteristics of alternating currents — practice question
An alternating current supply is connected in series with resistor R, as shown in Fig. 6.1. The current I in the resistor, with time t measured in seconds and I measured in amps, varies according to the expression I = 9.9\sin(380t).
(a(i))[2]
Determine the frequency of the current in resistor R.
(a(ii))[2]
Determine the r.m.s. current for the current in resistor R.
(b)[2]
To avoid overheating, the mean power dissipated in resistor R must stay below 400\text{ W}. Calculate the minimum resistance of R.
Worked solution & mark scheme
This 6-mark question has a full step-by-step worked solution and mark scheme. One marking point: “Applying 2\pi f = 380” …