Basic Electrical Science (Practice Test)

1) Two equal resistors R connected in series across a voltage source V dissipate power P. What would be the power dissipated in the same resistors when they are connected in parallel across the same voltage source ?
A. 4P
B. P
C. 2P
D. 16P

2) Two identical resistors are first connected in parallel then in series. The ratio of resultant resistance of the first combination to the second will be
A. 4
B. 0.25
C. 2
D. 0.5

3) The ratio of the resistance of a 200W, 230V lamp to that of a 100W, 115V lamp will be
A. 0.5
B. 2
C. 4
D. 0.25

4) The resistance of 200W 200V lamp is
A. 100 Ω
B. 200 Ω
C. 400 Ω
D. 800 Ω

5) Two 1 kΩ 1 W resistors are connected in series. Their combine resistance and wattage will be
A. 2 kΩ, 0.5 W
B. 1 kΩ, 1 W
C. 0.5 kΩ, 2 W
D. 2 kΩ, 1 W

6) Three 3 Ω resistors are connected to form a triangle. What is the resistance between any two of the corners ?
A. 9 Ω
B. 6 Ω
C. 3 Ω
D. 2 Ω.

7) A wire of 0.14 mm diameter and specific resistance 9.6 μΩ - cm is 440 cm long. The resistance of the wire will be
A. 9.6 Ω
B. 11.3 Ω
C. 13.7 Ω
D. 27.4 Ω

8) A 10 Ω resistor is stretched to increase its length double. Its resistance will now be
A. 40 Ω
B. 20 Ω
C. 10 Ω
D. 5 Ω

9) Specific resistance is measured in
A. mho
B. ohm
C. ohm - cm
D. ohm/cm

10) A wire of resistance R has it length and cross - section both doubled. Its resistance will become
A. 0.5R
B. R.
C. 2R
D. 4R

11) 5 1016 electrons pass across the section of a conductor in 1 minutes and 20 seconds. The current flowing is
A. 0.1 mA.
B. 1 mA
C. 10 mA
D. 100 mA

12) Three element having conductance G1, G2 and G3 are connected in parallel. their combined conductance will be
A. (G1 + G2 + G3)-1
B. G1 + G2 + G3
C. 1/G1 + 1/G2 + 1/G3
D. (1/G1 + 1/G2 + 1/G3)-1

13) Which of the following has negative temperature coefficient ?
A. Electrolytes.
B. Brass.
C. Copper.
D. Silver.

14) Which of the following has positive temperature coefficient ?
A. Germanium.
B. Gold
C. Paper
D. Rubber

15) A 60 W bulb in series with a room heater is connected across the mains. If the 60 W bulb is replaced by 100 W bulb
A. the heater output will increase
B. the heater output will decrease
C. the heater output will be same
D. the heater output will slightly decrease.

16) A cube of material of side 1 cm has a resistance of 0.002 Ω between its opposite faces. If the same volume of the material has a length of 4 cm and a uniform cross - section, the resistance of this length will be
A. 0.128 Ω
B. 0.064 Ω
C. 0.032 Ω
D. 0.016 Ω