Electrical Engineering- Electric Current and Ohm's Law
Electrical Engineering- Electric Current and Ohm's Law
The shunt winding of a motor has a resistance of 85 ohm at 22oC. When the motor runs at full load, its resistance increases to 100 ohms. The resistance temperature coefficient of winding per 0oC is 0.004. The rise in temperature of the winding will be nearly
- 20oC
- 50oC
- 70oC
- 100oC.
The resistance temperature coefficient is defined as
- ) increase in resistance per degree centigrade
- decrease in resistance per degree centigrade
- the ratio of increase in resistance per degree centigrade to the resistance at 0oC
- the ratio of increases in resistance per degree centigrade to the rate of rise of resistance at 0oC.
Two coils connected in series have resistance of 600 ohm and 300 ohm and temperature coefficients of 0.1% and 0.4% respectively.The resistance of the combination at 50oC will be
- 1050 ohm
- 1001 ohm
- 1600 ohm
- 990 ohm.
A 100 W, 200 V filament lamp has operating temperature of 2000oC. The filament material has resistance temperature coefficient of 0.005 at 0oC per oC. The current taken by the lamp at the instant of switching with 200 V supply with filament temperature of 20oC will be
- 1 A
- 3 A
- 5 A
- 10A.
- Silver
- Copper
- Aluminium
- Carbon.
The voltage drop will be least in which resistor ?
- 2 ohm
- 3 ohm
- 6 ohm
- 3 ohm and 6 ohm.