AC Circuits

What is a passive component?

• Resistor

• Capacitor

• Inductor

• Transistor

The use of inductor?

• Passive component that stores food in a fridge when electric current flows through it.

• Passive component that stores energy in a magnetic field when electric current flow through it

• Passive component that stores electric charge in an AC circuit.

• Passive component that limits the current flow.

What is period

• Time required for a sine wave to complete one full cycle.

• It is equal to frequency.

• Unit = second

• T = 1/f

What is amplitude?

• V_pp or I_pp

• V_rms or I_rms

• V_p or I_p

• Positive or Negative maximum value of the sine wave

What is root mean square, rms?

• Can be read using multimeters

• The main supply in our home is 240V. So this is rms value.

• V_rms = 0.707 × V_p

• Also known as Effective voltage.

A heater is rated as 230 V, 10 kW. The value 230 V refers to

• average voltage
• r.m.s voltage
• peak voltage

The r.m.s value of an alternating current is given by steady (D.C) current which when flowing through a given circuit for a given time produces

• the more heat that is produced by A.C when flowing through the same circuit

• the less heat that is produced by A.C when flowing through the same circuit

• the same heat that is produced by A.C when flowing through the same circuit

If a sinusoidal wave has a frequency of 50 Hz with 30 A r.m.s current, which of the following equation represents the wave?

• 42.42 sin 314.2t
• 60 sin 25t
• 30 sin 50t
• 84.84 sin 25t

Why is it necessary to deal with AC waveforms?

• Because electric power is most likely generated in the shape of AC

• Because it is easier than DC

• Because it is more widely spread

• Because it is more efficient

For a given AC waveform

• The shorter the period, the lower the frequency

• The shorter the period, the higher the frequency

• The longer the period, the lower the frequency

• The longer the period, the higher the frequency