# Electrical Circuit Theory Problems and Solutions

There are three essential laws governing the electrical circuit. These are Ohm’s Law, Kirchhoff’s Current Law and Kirchhoff’s Voltage Law. Basically these are utilized to solve any electrical circuit problem.

Ohm’s Law states that voltage across a resistance is current passing through it times the resistance. $V=I\times R$

Kirchhoff’s Current Law (KCL)  states that at any junction, the sum of incoming currents is equal to sum of outgoing currents, $\sum I_i=\sum I_o$

Kirchhoff’s Voltage Law (KVL) states that sum of voltage rises is equal to sum of voltage drops around a closed loop, $\sum V_r=\sum V_d$

Solutions for electrical circuit (network) problems can be arrived at by using the following theorems / laws.

• Ohm’s Law
• Kirchhoff’s Current Law (KCL)
• Kirchhoff’s Voltage Law (KVL)
• Thevenin’s Theorem
• Norton’s Theorem
• Superposition Theorem
• Mesh Analysis
• Nodal Analysis
• Source Transformation
• Star-Delta Transformation (aka Wye-Delta)
• Tellegen’s Theorem
• Bartlett’s Bisection Theorem
• and other shortcut methods

## Multiple Choice Questions

Q01. The amount of work done in moving a unit positive
charge from one point to another is,

(a) Charge
(b) Potential Difference
(c) Resistance
(d) Capacitance


Q02. The potential difference between two points is
said to be ______, if 1 Joule of work is done in moving
1 Coulomb of electric charge from one point to another

(a) 1 milliVolt
(b) 1 megaVolt
(c) 1 kiloVolt
(d) 1 Volt


Q03. Charge of an electron (e) = _____ C

(a) 1.6 x 10-11
(b) 3.2 x 10-19
(c) 1.9 x 10-16
(d) 1.6 x 10-19


Q04. 1 Volt = ________

(a) 1 milliVolt
(b) 1000 milliVolt
(c) 0.1 kiloVolt
(d) 1 microVolt


Q05. Ohm’s Law can mathematically be stated as:
(Symbols have their usual meanings)

(a) C = I x A
(b) A = I x V
(c) R = I x C
(d) V = I x R


Q06. If 2 Ampere current flows through the conductor
when 15 Volt potential difference is applied across it, the
resistance is ____ Ohm

(a) 30
(b) 5
(c) 7.5
(d) 1


Q07. Effective Resistance of resistors in Parallel
is ________ of all resistors

(a) Less than Maximum
(b) Less than Least
(c) More than Maximum
(d) More than Least


Q08. The quantity of heat (H) generated in a conductor
of Resistance (R), when a current (I) flows through it for
the time (t), depends on

(a) Current (I)
(b) Resistance of conductor (R)
(c) Time for which current flows (t)
(d) All of the above
Ans:


Q09. Resistivity of Ebonite is ______ (ohm-m)

(a) 10-8 to 10-6
(b) 103 to 105
(c) 107 to 108
(d) 1015 to 1017


Q10. Effective Resistance of resistors in Series
is ________ of all resistors

(a) Less than Maximum
(b) Less than Minimum
(c) More than Maximum
(d) More than Minimum


Q01. (b) Potential Difference
Q02. (d) 1 Volt
Q03. (d) 1.6 x 10-19
Q04. (b) 1000 milliVolt
Q05. (d) V = I x R
Q06. (c) 7.5
Q07. (b) Less than Least
Q08. (d) All of the above
Q09. (d) 1015 to 1017
Q10. (c) More than Maximum