1. When current flows through heater coil it glows but supply wiring does not glow because ?

current through supply line flows at slower speed

supply wiring is covered with insulation layer

resistance of heater coil is more than the supply wires

supply wires are made of superior material

Answer: resistance of heater coil is more than the supply wires

Explanation:


2. ...... are the materials having electrical conductivity much less than most of the metals but much greater than that of typical insulators ?

Varistors

Thermistor

Semi-conductors

Variable resistors

Answer: Semi-conductors

Explanation:


3. Switching of a lamp in house produces noise in the radio. This is because switching operation produces ?

arcs across separating contacts

mechanical noise of high intensity

both mechanical noise and arc between contacts

none of the above

Answer: arcs across separating contacts

Explanation:


4. Which method can be used for absolute measurement of resistances ?

Lorentz method

Releigh method

Ohm's law method

Wheatstone bridge method

Answer: Wheatstone bridge method

Explanation:


5. Which of the following can have negative temperature coefficient ?

Compounds of silver

Liquid metals

Metallic alloys

Electrolytes

Answer: Electrolytes

Explanation:


6. Three identical resistors are first connected in parallel and then in series. The resultant resistance of the first combination to the second will be ?

9 times

1/9 times

1/3 times

3 times

Answer: 1/9 times

Explanation:


7. Resistance of 220 V, 100 W lamp will be ?

4.84 ?

48.4 ?

484 ?

4840 ?

Answer: 484 ?

Explanation:


8. With three resistances connected in I parallel, if each dissipates ,20 W the total power supplied by the voltage source equals ?

10W

20 W

40 W

60 W

Answer: 60 W

Explanation:


9. which resistor will be physically larger in size ?

100 ?, 10W

10 ?, 50 W

1 M?, 1/2 W

1 k?, 1 W

Answer: 10 ?, 50 W

Explanation:


10. A resistance having rating 10 ohms, 10 W is likely to be a ?

metallic resistor

carbon resistor

wire wound resistor

variable resistor

Answer: wire wound resistor

Explanation: