### Basic Electrical Science (Practice test)

1) Resistivity of a wire depends on

A. material

B. length

C. cross section area

D. all of above

2) When n numbers resistances of each value
r are connected in parallel, then the resultant resistance is x. When these n
resistances are connected in series, total resistance is

A. nx.

B. n

^{2}x.
C. x/n.

D. rnx.

3) Resistance of a wire is r ohms. The wire
is stretched to double its length, then its resistance will be

A. r/2

B. 4r

C. 2r

D. r/4

4) Kirchhoff's second law is based on law
of conservation of

A. charge

B. energy

C. momentum

D. mass

5) One coulomb of electrical charge is
contributed by how many electrons ?

A. 0.625
X 10

^{19}.
B. 1.6
X 10

^{19}.
C. 10

^{19}.
D. 1.6
X 10

^{12}.
6) Tow bulbs marked 200 watts - 250 V, and 100
watts - 250 V are joined in series to 250 V supply. The power consumed by the
circuit is

A. 33
watt

B. 200
watt

C. 300
watt

D. 67
watt.

7) Ampere second is the unit of

A. conductance

B. power

C. energy

D. charge

8) Which of the following is not the unit
of electrical power

A. volt/ampere

B. volt
ampere

C. watt

D. joule/second

9) One kilowatt hour is same as

A. 36
X 10

^{5}watt
B. 36
X 10

^{5}ergs
C. 36
X 10

^{5}joules
D. 36
X 10

^{5}BTU
10) An electric current of 6 A is same as

A. 6
joule/second

B. 6
Coulomb/second.

C. 6
watt/second

D. none
of the above.

11) A circuit contains two un equal
resistor in parallel

A. voltage
drops across both are same

B. currents
in both are same

C. heat
losses in both are same

D. voltage
drops are according to their resistive value

12) Conductance of any conductor is
expressed as

A. ampere/watt

B. mho

C. volt

^{2}/watt
D. watt/ampere

^{2}
13) A copper wire of length l and diameter
d has potential difference V applied at its two ends. The drift velocity is vd.
If the diameter of the wire is made d/2, then the drift velocity becomes

A. vd.

B. 4vd.

C. vd/4.

D. vd/2.

14) Two resistances R

_{1}and R_{2}give combined resistances 4.5Ω and 1Ω when they are connected in series and parallel respectively. What would be the values of these resistances ?
A. 3Ω
and 6Ω

B. 1.5Ω
and 3Ω

C. 3Ω
and 9Ω

D. 6Ω
and 9Ω

15) Which of the following may be value of
resistivity of copper

A. 1.7
X 10

^{-6}
B. 1.7
X 10

^{-5}
C. 1.7
X 10

^{-4}
D. 1.7
X 10

^{-3}
16) Mass of a proton is how many times
greater than mass of an electron

A. 184000

B. 18400

C. 1840

D. 184

**Answers**

1. a 2.
b 3. b 4. b 5. a 6. d 7.
d 8. a 9. c 10. b

11. a 12.
b 13. a 14.
b 15. a 16.
c

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