## Quiz sheet for phasor diagrams

Phasors are quantities which vary in

A) magnitude, direction and time

B) magnitude and time only

C) rms value

D) I like eating bananas

ANSWER: A

Phasors normally:

A) rotate in a anticlockwise direction

B) rotate in a clockwise direction

C) have linear velocity only

D) do not have a definite direction or velocity

ANSWER: A

The purpose of a phasor diagram is to

A) make students think that they are dumb so that only the best students pass the course.

B) calculate the sum of two constantly changing values that are out of phase with each other.

C) find the total voltage in a series circuit that has inductors in it.

D) explain how dirty power is causing too much current to run through the cables.

ANSWER: B

The value of line voltage which is used on appliance rating plates for AC supply is

A) rms value

B) instantaneous value

C) peak value

D) average value

ANSWER: A

The length of a voltage phasor represents the

A) rms value

B) instantaneous value

C) average value

D) peak value

ANSWER: A

If the load connected to an AC supply is purely resistive the current will

A) be in phase with the voltage

B) lead the voltage

C) lag the voltage

D) hunt the voltage

ANSWER: A

The average value of a sine wave over a full cycle is:

A) zero

B) 2

C) 0.707

D) 0.637

ANSWER: A

If a capacitor and a resistor are connected to an AC supply the current will

A) be in phase with the voltage

B) lead the voltage

C) lag the voltage

D) hunt the voltage

ANSWER: B

If the two wave forms representing respective voltage drops in a two resistor series AC circuit and displayed on a CRO simultaneously, the waves would

A) be in phase

B) lag by 90 degrees electrical

C) be added together ~give a single square wave

ANSWER: A

The peak value of a sine wave is given by

A) the r.m.s value divided by 0.707

B) the r.m.s. value divided by 0.637

C) the r.m.s. value multiplied by 0.707

D) the r.m.s.value multiplied by 0.637}

ANSWER: A

If a motor is connected to an AC supply, the current will

A) be in phase with the voltage

B) lead the voltage

C) lag the voltage

D) hunt the voltage

ANSWER: C

The rms value of a sine wave is equivalent to

A) the heating effect of a similar value of DC current

B) the average value of one positive

C) the average value of one complete sine

D) the real maximum square value

ANSWER: A