Multi-choice questions on resistance variation

1. The unit of resistivity is:
(a) ohms
(b) ohm millimetre
(c) ohm metre
(d) ohm/metre
2. The length of a certain conductor of resistance
100Ω is doubled and its cross-sectional area
is halved. Its new resistance is:
(a) 100Ω (b) 200Ω
(c) 50Ω (d) 400Ω
3. The resistance of a 2 km length of cable of
cross-sectional area 2mm2 and resistivity of
2×10−8 Ωm is:
(a) 0.02Ω (b) 20Ω
(c) 0.02mΩ (d) 200Ω
4. A piece of graphite has a cross-sectional area
of 10mm2. If its resistance is 0.1Ω and its
resistivity 10×108 Ωm, its length is:
(a) 10 km (b) 10 cm
(c) 10mm (d) 10m
5. The symbol for the unit of temperature coefficient
of resistance is:
(a) Ω/
◦C (b) Ω
(c) ◦C (d) Ω/Ω
◦C
6. A coil of wire has a resistance of 10Ω at 0◦C.
If the temperature coefficient of resistance for
the wire is 0.004/
◦C, its resistance at 100◦C is:
(a) 0.4Ω (b) 1.4Ω
(c) 14Ω (d) 10Ω
7. A nickel coil has a resistance of 13Ω at 50◦C.
If the temperature coefficient of resistance at
0◦C is 0.006/
◦C, the resistance at 0◦C is:
(a) 16.9Ω (b) 10Ω
(c) 43.3Ω (d) 0.1Ω
8. A colour coding of red-violet-black on a resistor
indicates a value of:
(a) 27Ω ±20% (b) 270Ω
(c) 270Ω±20% (d) 27Ω±10%
9. Aresistor marked as4K7Gindicates a value of:
(a) 47Ω±20% (b) 4.7 kΩ±20%
(c) 0.47Ω±10% (d) 4.7 kΩ±2%