Current Electricity Questions and Answers - Set 01 - ObjectiveBooks

# Practice Test: Question Set - 01

1. Which of the following statement is true both for a series and a parallel D.C. circuit?
(A) Elements have individual currents

2. Insulating materials have the function of
(A) Preventing a short circuit between conducting wires
(B) Preventing an open circuit between the voltage source and the load
(C) Conducting very large currents
(D) Storing very high currents

3. The hot resistance of the bulb's filament is higher than its cold resistance because the temperature coefficient of the filament is
(A) Zero
(B) Negative
(C) Positive
(D) About 2 ohms per degree

4. Resistance of a material always decreases if
(A) Temperature of material is decreased
(B) Temperature of material is increased
(C) Number of free electrons available becomes more
(D) None of the above is correct

5. In the case of direct current
(A) Magnitude and direction of current remains constant
(B) Magnitude and direction of current changes with time
(C) Magnitude of current changes with time
(D) Magnitude of current remains constant

6. Two copper conductors have equal length. The cross-sectional area of one conductor is four times that of the other. If the conductor having smaller cross-sectional area has a resistance of 40 ohms the resistance of other conductor will be
(A) 160 ohms
(B) 80 ohms
(C) 20 ohms
(D) 10 ohms

7. Which of the following statement is correct?
(A) A semiconductor is a material whose conductivity is same as between that of a conductor and an insulator
(B) A semiconductor is a material which has conductivity having average value of conductivity of metal and insulator
(C) A semiconductor is one which conducts only half of the applied voltage
(D) A semiconductor is a material made of alternate layers of conducting material and insulator

8. Which of the following can have negative temperature coefficient?
(A) Compounds of silver
(B) Liquid metals
(C) Metallic alloys
(D) Electrolytes

9. An instrument which detects electric current is known as
(A) Voltmeter
(B) Rheostat
(C) Watt-meter
(D) Galvanometer

10. Four wires of same material, the same cross-sectional area and the same length when connected in parallel give a resistance of 0.25 Q. If the same four wires are connected is series the effective resistance will be
(A) 1 Q
(B) 2 Q
(C) 3 Q
(D) 4 Q

11. Sparking occurs when a load is switched off because the circuit has high
(A) Resistance
(B) Inductance
(C) Capacitance
(D) Impedance

12. International ohm is defined in terms of the resistance of
(A) A column of mercury
(B) A cube of carbon
(C) A cube of copper
(D) The unit length of wire

13. An open resistor, when checked with an ohmmeter reads
(A) Zero
(B) Infinite
(C) High but within tolerance
(D) Low but not zero

14. The number of electrons in the outer most orbit of carbon atom is
(A) 3
(B) 4
(C) 6
(D) 7

15. A field of force can exist only between
(A) Two molecules
(B) Two ions
(C) Two atoms
(D) Two metal particles

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