This document contains a series of questions and problems related to basic electrical concepts such as charge, current, voltage, power, energy, Ohm's law, Kirchhoff's laws, and resistor networks. The questions cover topics like calculating charge, current, power, and energy in circuits; applying Kirchhoff's laws to determine voltages and currents; analyzing series and parallel resistor networks; and using techniques like star-delta transformations. Solutions are provided for some of the example circuit analysis problems. The document appears to be from a textbook or class on basic electrical and electronic engineering concepts.

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BANGLADESH UNIVERSITY OF TEXTILES
TEJGAON, DHAKA-1208
B.Sc. in Textile Engineering
Electrical and Electronic Engineering
EEE-1
 Basic Concepts
 Basic Laws
Date: 19/02/2017

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Question
1.1) Define charge, current, voltage, power and energy.
2.1) Differentiate between passive element and active element.
3.1) Differentiate between dependent source and independent source.
4.1) Draw and explain the terminal characteristics of DC and AC voltage and current sources.
5.1) State and explain Ohm’s law, KVL and KCL.
6.1) What is node, branch and loop? Explain.
7.1) Explain the current division and voltage division rule.

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Problem
8.1) A rechargeable flashlight battery is capable of delivering 85mA for about 12h. How much charge can it
release at that rate? If its terminals voltage is 1.2V, how much energy can the battery deliver?
Solution:
9.1) A 60W, incandescent bulb operates at 120V. How many electrons and coulombs flow through the bulb
in one day?
Solution:
10.1) Charge is flowing through a conductor at the rate of 420 C/min. If 742J of electrical energy are
converted to heat in 30 s, what is the potential drop across the conductor?
Solution:
11.1) The potential difference between two points in an electric circuit is 24 V. If 0.4 J of energy were
dissipated in a period of 5 ms, what would the current be between the two points?
Solution:
12.1) If a conductor with a current of 200 mA passing through it converts 40 J of electrical energy into heat
in 30 s, what is the potential drop across the conductor?
Solution:

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13.1) Between two points in an electric circuit, a voltmeter reads 12.5 V for a period of 20 s. If the current
measured by an ammeter is 10 mA, determine the energy expended and the charge that flowed between the
two points.
Solution:
14.1) A battery may be rated in ampere-hours (Ah). A lead-acid battery is rated at 160Ah.
a) What is the maximum current it can supply for 40h?
b) How many days will it last if it is discharged at 1mA?
Solution:
15.1) A calculator with an internal 3-V battery draws 0.4 mW when fully functional.
a.What is the current demand from the supply?
b.If the calculator is rated to operate 500 h on the same battery, what is the ampere-hour rating of the
battery?
Solution:
16.1)
a.In 10 h an electrical system converts 1200 kWh of electrical energy into heat. What is the power level of the
system?
b.If the applied voltage is 208 V, what is the current drawn from the supply?
c. If the efficiency of the system is 82%, how much energy is lost or stored in 10 h?
Solution:

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17.1) A standard 12-V car battery has an ampere-hour rating of 40 Ah, whereas a heavy-duty battery has a
rating of 60 Ah. How would you compare the energy levels of each and the available current for starting
purposes?
Solution:
18.1) A constant current of 3A for 4hours is required to charge an automotive battery. If the terminal voltage
is 10+t/2 Volt, where t is in hours,
a) how much charge is transported as a result of the charging?
b) how much energy is expended?
c) how much does the charging cost? Assume electricity costs 9 cents/kWh.
Solution:

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19.1) In the circuit in Figures, obtain v1 , v2 and v3.
Solution:
20.1) Given the circuit in Figure, use KVL to find the branch voltages V1 to V4.
Solution:

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21.1) Find the unknown voltage V1 in the circuit of Figure.
Solution:
Taking the outer closed loop ABCDEFA and applying KVL to it, we get
− 16 × 3 − 4 × 2 + 40 − V1 =0 ; ∴ V1 = -16 V
The negative sign shows there is a fall in potential.
22.1) Find i1, i2 and i3 in the figure.
Solution:

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23.1) For the circuit in Figure, use KCL to find the branch currents to I1 to I4.
Solution:

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24.1) In the network of Figure, the different currents and voltages are as under :
i2 = 5e− 2t
, i4 = 3sint and v3 = 4e− 2t
. Using KCL, find voltage v1.
Solution:

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25.1) In the network shown in Figure below, v1 = 4V, v4 = 4 cos2t and i3 = 2e−t/3
. Determine i2.
Solution:
26.1) A 50-ohm resistor is in parallel with 100-ohm resistor. Current in 50-ohm resistor is 7.2 A. How will
you add a third resistor and what will be its value of the line-current is to be its value if the line-current is
to be 12.1 amp ? [Answer: 227Ohm]
Solution: Source voltage = 50 × 7.2 = 360 V, Current through 100–ohm resistor = 3.6 A
Total current through these two resistors in parallel = 10.8 A
For the total line current to be 12.1 A, third resistor must be connected in parallel, as the third branch, for
carrying (12.1 − 10.8) = 1.3 A. If R is this resistor R = 360/1.3 = 277 ohms

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27.1) A circuit consists of four 100-W lamps connected in parallel across a 230-V supply. Inadvertently, a
voltmeter has been connected in series with the lamps. The resistance of the voltmeter is 1500 Ω and that
of the lamps under the conditions stated is six times their value then burning normally. What will be the
reading of the voltmeter?[ 150V (approx)]
Solution:
The circuit is shown in Fig. 1.18. The wattage of a lamp is given by :
W = I2
R = V2
/R
∴ 100 = 2302
/R ∴ R = 529 Ω
Resistance of each lamp under stated condition is =6×529=3174 Ω
Equivalent resistance of these four lamps connected in parallel = 3174/4 = 793.5 Ω
This resistance is connected in series with the voltmeter of 1500 Ω resistance.
∴ total circuit resistance =1500+793.5=2293.5 Ω
∴ circuit current =230/2293.5 A
According to Ohm’s law, voltage drop across the voltmeter =1500×230/2293.5=150V(approx)
28.1) Find the current supplied by the battery in the circuit. [Answer: 5A, 9A, 15A]
(i) (ii) (iii)
Solution: (Try to solve)
29.1) What is the equivalent resistance of the circuit of Figure between terminals A and B? All resistances
are in ohms. [4 Ω].
Solution: [Try to solve]

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30.1) Compute the value of battery current I in Figure. All resistances are in ohm.[ Answer: 6 A]
31.1) Find RAB in the circuit. [Answer: 22.5 ohms ]
Solution:

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32.1) In Figure if all the resistances are of 6 ohms, calculate the equivalent resistance between any two
diagonal points.[Answer: 3 Ohm]
Solution:

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33.1) Calculate the equivalent resistance in the circuit in Figure.
Solution:

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34.1) Obtain the equivalent resistance Rab for the circuit in Figure and use it to find current i.
Solution:

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35.1) Obtain the equivalent resistance at the terminals a-b for each of the circuits in Figures.
Question: 1.35(a)
Solution:
Question: 1.35(b)
Solution:

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Question: 1.35(c)
Solution:

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36.1) Calculate the indicated currents and voltage of Figure.
Solution:

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37.1) For the multiple ladder configuration of Figure:
a. Determine I.
b. Calculate I4.
c. Find I6.
d. Find I .
Solution:

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38.1) Calculate the equivalent resistance between the terminals A and B in the network shown in Fig. 2.187
(a).
Solution:
39.1) Calculate the current flowing through the 10 Ω resistor of Fig. 2.188 (a) by using any method.
Solution:

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40.1) A bridge network ABCD has arms AB, BC, CD and DA of resistances 1, 1, 2 and 1 ohm respectively. If
the detector AC has a resistance of 1 ohm, determine by star/delta transformation, the network resistance
as viewed from the battery terminals.
Solution:
41.1) Use delta-star conversion to find resistance between terminals ‘AB’ of the circuit shown in Fig. 2.193
(a). All resistances are in ohms.
Solution:

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