Electrical Engineering Quiz

What is Alternating Current?

• Electric current that changes direction periodically only.

• Electric current that flows in one direction only.

• Electric current that is generated by a battery.

• Electric current that flows through a capacitor.

A phasor represents

• The width of a quantity

• The magnitude and a quantity direction

• The phase angle

• The magnitude of a quantity

An alternating current dynamo was connected with a resistance of 40Ω, resulting in a thermal power of 4000 watts. The maximum value for both current and potential difference are:

• and 400

• (6 and 240)

• (7 and 280)

• (14 and 560)

In a pure inductive circuit if frequency is reduced to 1/2, the current will be

• reduced by half

• doubled

• four times as high

• reduced to one fourth

Three capacitors for each capacitance 14μf connected in parallel with the source of its frequency 50 Hz. Then the capacitive reactance of total capacitance.

• 681.8Ω

• 322.3Ω

• 151.5Ω

• 75.76Ω

In a series R-L circuit.

• Voltage drops across R and L are in phase.

• Voltage drop across L leads the voltage drop across R by 90∘.

• Voltage drop across L lags behind the voltage drop across R by 90∘.

• Voltage drops across R and L are in phase opposition.

The time constant of a series RC circuit is given by

• R/C

• RC²

• RC

• R²C

An AC circuit consisting of a resistance R, inductance coil L and capacitor C connected on series and it was XC​=2XL​=2R then the total potential difference:

• Leads by 90∘ with VR​

• Leads by 45∘ with VR​

• Lags by 90∘ with VR​

• Lags by 45∘ with VR​

In a circuit RLC Series connected resonance occurs when:

• XL​−Xc​

• XL​=Xc​

• XL​

• XL​>Xc​

A complex number in a vertical form (4+j3) whose polar form is.

• 5∠37∘

• 7∠37∘

• 7∠7∘

• 5∠−37∘