A level Alternating current

A resistor is connected to an AC power supply. On this circuit, the current

• leads the voltage by 90°.

• lags the voltage by 90°.

• is in phase with the voltage.

• none of the given answers

What does AC smoothing mean?

• the process of inducing an emf (voltage) with a change in magnetic flux

• Electric currents whose direction and magnitude change periodically depending on time are called alternating current

• Steady current which delivers the same average power as the a.c. to a resistive load.

• Making a rectified current more steady (or smooth) by placing a capacitor in parallel with the resistor​

What is alternating current

• the process of inducing an emf (voltage) with a change in magnetic flux

• Electric currents whose direction and magnitude change periodically depending on time are called alternating current

• Steady current which delivers the same average power as the a.c. to a resistive load.

• Making a rectified current more steady (or smooth) by placing a capacitor in parallel with the resistor​

If the Y-sensitivity and time-base for the trace shown in Figure are 5 V/cm and 20 ms/cm, what are the amplitude, period and frequency of the signal to Y-input?

• 3.5 V, 80 ms, 50 Hz

• 20 V, 40 ms, 50 Hz

• 17.5 V, 80 ms, 12.5 Hz

• 22.5 V, 12.5 ms, 55 Hz

Which image shows the output of a sine-wave after it has gone through a diode? (Half-wave rectified)

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The instantaneous current in an ac circuit is i=2.0 sin314t, what is rms value of the current.

• 1.414 A

• 2.828A

• 1 A

• 2 A

The electricity in our house is

• AC

• DC

• BC

• AD

Which of the following general equations represent AC current

rms value of ac current is the equivalent direct current which produces

• the same average energy

• the same power dissipation

• the same rate of current flow

• the same rate of power use

A pure resistor is connected to an a.c. source where its current is given by I=5.0 sin 628t. Which of the following statements is not true about the circuit?

• The peak value of current flowing through the resistor is 5.0 A

• The root mean square current flowing through the resistor is 3.5 A

• The frequency of the current flowing through across the resistor is 120 Hz

• The equivalent direct current which gives the same average heating power in the resistor is 3.5 A