1.

Calculate the mean drift velocity of the

electrons in a copper wire of cross sectional area
5.0x10-6m2 carrying a current of 1.0 A. There are
8.5 x106 free electrons in one m3 of copper.
A.1.5 X1019 B.1.5 X1019
C.1.5 X1019 D.1.5 X1019
2.What Is the product of electrical conductivity
of the materials & Electric field (E).
A. charge density B. current density
C. Effective density D. current
3.Four resistors are connected to a voltage source as shown in the
circuit diagram shown below . What are the current through the 3Ω
resistor and the voltage drop across 4ΩΩ resistor ,respectively?
A.2/3A & 4V B.2A &3/4V C.4/3A &8V D.3/4A &8V

3Ω

6Ω 1Ω
14v

4Ω
4.What is the potential difference across R 1?
A. 4v B.2v C. 8v D.10v

1Ω

4Ω 2Ω
14v
5.The total resistance two identical resistors
when connected in parallel is 40Ω.if these the
same resistors are connected in series their
equivalent resistance will be:
A.20Ω B. 160Ω C. 0.1Ω D. 80Ω
6. find the electric current density ,in the wire of
area 2m2 &the flow of electric current in the
wire is 40A.
A. 20 A/m2 B.2A/ m2
C. 40 A/m2 D. 4 A/m2
7.A battery has an e.m.f of 10v & an internal
resistance of 2Ω. Find the current it supplied to
the resistor with 12Ω.
A. 7A B.0.7A C.8A D. 0.8A
8. A battery has an e.m.f of 100V of and internal resistance of
2Ω. Calculate the power used in the external resistance of 4
Ω
A. 2.5kW B.1.1kW C.4.8kW D.6.2kW
9. A battery having an emf of 9 V delivers 117 mA when
connected to a 72Ω load.
Determine the internal resistance of the battery.
A.5Ω B. 10Ω C.9Ω D.3Ω
10. (a) Find the current in an 8Ω resistor connected to a
battery that has an internal resistance of 0.15 Ω if the voltage
across the battery (the terminal voltage) is 9 V.
A. 1.125A B. 2.125A C. 0.125A D. 3.125A
(b) What is the emf of the battery?
A.12.2v B. .9.2v C.19.2v D. 23.2v
11.Calculate,
A. the equivalent resistance
B. B. current in each resistors .
C. C. voltage across each resistors
12. Which one of the following is correct?
A. The equivalent resistance of two or more
resistors connected in parallel is always less than
the least resistance in the group.
B. The equivalent resistance of two or more
resistors connected in series is always greater
than the highest resistance in the group.
C. The effective resistance of resistors connected
in parallel is smaller than the total resistance
connected in series.
D.all
13.A copper wire of cross sectional area 2mm2 carrying a
current of 1.5A.if the drift velocity of the electron is
0.0028m/s, what is the number of charge carriers (free
electrons) per unit volume in the copper wire? 2010
A.1.67 x 1027 B.1.67 x 1028
C. 6.7 x 1028 D.6.7 x 1028
14.A circuit provides a maximum current of 20A at an
operating voltage of 1.2 x 102 V.
(a) How many 75.0 W bulbs can operate with this
voltage source?
A.32 B.64 C.96 D.48
(b) At 0.120 birr per kilowatt - hour, how much does it
cost to operate these bulbs for 8.00 h?
A. 19.2birr B.2.3 birr C.2.4birr D.9.6birr
15.a)What is the equivalent resistance
of the circuit shown in the figure?
A.65.5Ω B.9.5Ω C.6.5Ω D.13.5Ω
16. A cell of emf 1.5 V and internal resistance 0.5
Ω is connected to a 2.5 Ω resistor.
Calculate:
(a) the current (b) the terminal p.d,
(b) the power delivered to the 2.5 Ω resistor
and (c) the power wasted in the cell.
17. The p.d across the terminals of a cell was 1.1
V when the current from the cell was 0.20 A,
and 1.3 V when the current was 0.10 A.
Calculate:
(a) the internal resistance of the cell,
A.4Ω B.2Ω C.6Ω D.8Ω
b/ the cell’s emf.
A. 1.5V B.2V C.1.4V D.1.6V
18. A galvanometer with a resistance of 36Ω is
converted into an ammeter using a shunt
resistance of 4Ω. What fraction of the total
current passes through the galvanometer?
A.0.6 B. 0.1 C.0.2 D.0.4
19. A current of 0.3 A is passed through a lamp
for 2 minutes using a 6-V power supply. The
energy dissipated by this lamp during the 2
minutes is:
A.1.2J B.12J C.216J D.36J
20. Four 20-Ω resistors are connected in parallel
and the combination is connected to a 20-V emf
device. The current in the device is:
A. 0.25A B.1A C.4A D.5A
21. Four 20-Ω resistors are connected in parallel
and the combination is connected to a 20-V emf
device. The current in any one of the resistors is:
A.0.25A B.1A C.4A D.5A
22. Four 20-Ω resistors are connected in series
and the combination is connected to a 20-V emf
device. The current in any one of the resistors is:
A.0.25A B.1A C.4A D.5A
23. A 220-V power line is protected by a 20A
fuse. What is the maximum number of “220 V,
600W” light bulbs that can be operated at full
brightness from this line?
A. 6 B.7 C.8 D.9
24.To make a galvanometer into an ammeter,
connect:
A. a high resistance in parallel
B. a high resistance in series
C. a low resistance in series
D. a low resistance in parallel
25. A certain galvanometer has an internal
resistance of 1 Ω and a range from 0 to 50 mA.
To make its range from 0 to 5 A, use:
A. a series resistance of 99 Ω
B. an extremely large (say 106 Ω ) series
resistance
C. a resistance of 99 Ω in parallel
D. a resistance of 1/99 Ω in parallel
26. A galvanometer has an internal resistance of
12 Ω and requires 0.01 A for full scale deflection.
To convert it to a voltmeter reading 3 V full scale,
one must use a series resistance of:
A. 102 Ω B. 288 Ω
C. 300 Ω D. 360 Ω
27. A certain voltmeter has an internal resistance
of 10, 000 Ω and a range from 0 to 12 V. To extend
its range to 120 V, use a series resistance of:
A. 1, 111 Ω B. 90, 000 Ω
C. 100, 000 Ω D. 108, 000 Ω
28.A battery of potential difference 16v is
connected to a 30kΩ resistor. How many electrons
pass across the resistor in 5 minutes?
A.1 x1018 B.1 x1019
C.1 x1016 D.1 x1017
29.Two resistors having resistance A and B
connected in series have a combined resistance of
10Ω . When the resistors are combined in parallel
their combined resistance is 2.4Ω.what is the
value of A and B respectively?
A.5Ω and 5Ω B.4Ω and 6Ω
C.6Ω and 4Ω D.7Ω and 3Ω
30.A 300w refrigerator, a 1000w stove, a 700w
heater are connected in parallel to 100v main and
controlled by 25 A fuse . under what condition the
fuse melt?
A.When the refrigerator and the stove are
switched on.
B. When the heater and the stove are switched on.
C. When the refrigerator and the stove are
switched on.
D.When the heater, refrigerator and the stove are
switched on.
31.Look at the following 3 circuits and
Find I1,I2 and I3 for each circuits.