# Electric Circuits Questions and Answers – The International System of Units, Voltage and Current, Power and Energy

This set of Electric Circuits Questions and Answers focuses on “The International System of Units, Voltage and Current, Power and Energy”.

1. Which of the following is a defined quantity?
a) Pressure
b) Polarity
c) Money
d) Length

Explanation: The SI units are based on 7 defined quantities namely length, mass, time, electric current, thermodynamic temperature, amount of substance and also on the luminous intensity.

2. The basic unit for luminous intensity is
a) Ampere
b) Candela
c) Coulomb

Explanation: The unit for luminous intensity is candela and its symbol is cd.

3. Which of the following is a correct relation?
a) Giga>Mega>Tera
b) Mega>Tera>Giga
c) Tera>Mega>Giga
d) Tera>Giga>Mega

Explanation: Tera – 1012
Giga – 109
Mega – 106.

4. Charge is
a) Unipolar
b) Bipolar
c) Tripolar
d) Non – Polar in nature

Explanation: Charge is bipolar since it can be expressed in terms of positive and negative.

5. Separation of charge creates
a) Current
b) Voltage
c) Resistance
d) Friction

Explanation: An electric force called voltage is created by separation of charge where as an electric fluid called current is created by motion of charge.
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6. The energy per unit charge is
a) Voltage
b) Power
c) Current
d) Work

Explanation: Voltage, v=dw/dq and its SI unit is volt.

7. If charge q = 3t2 + 2 then current is given by
a) 6t + 2
b) 3t2
c) 6t
d) 3t2 + 2

Explanation: I = dq/dt = d/dt(3t2 + 2) = 6t.

8. If energy w = 200t2+ 99 et + 2 then calculate at 0.1 sec
a) 148.52
b) 149.41
c) 149.95
d) 148.39

Explanation: p=dw/dt
=400t +99et
=400(0.1) + 99e(0.1)
=149.41

9. For the following circuit power is given by

a) –Vi
b) Vi
c) 0
d) 1

Explanation: P = vi. The algebraic sign of power depends on movement of charge through the drop and rise of voltage.

10. ‘Positive Power’ meaning ___________
a) Power is being delivered to circuit
b) Power is being extracted from circuit
c) No power supply
d) Input and output powers are equal

Explanation: P > 0 means +ve Power
Being delivered
P < 0 means –ve Power
Being extracted.

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To practice all areas of Electric Circuits, here is complete set of 1000+ Multiple Choice Questions and Answers.

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