What is the phenomenon of electromagnetic induction ?
Charging a body
The process of generating magnetic field due to current passing through a coil
Producing induced current in a coil due to relative motion between a magnet and the coil.
The process of rotating the coil of an electric motor
If a resistor is added in parallel with one of equal resistance, the resistance of the combination
increases by a small fraction
is doubled
decreases by a small fraction
is halved
The quantity of heat generated in a conductor when a current flows through it is directly proportional to the (a) resistance of the conductor. (b) current carried by the conductor. (c) time for which the current flows
a,b and c
a and b only
b and c only
a and c only
Two light bulbs are marked 230 V; 75 W and 230 V; 150 W. If the first bulb has a resistance R, then what is the resistance of the second bulb?
¼ R
½ R
2 R
4R
The resistance across AB is
4 Ω
1Ω
2 Ω
1.5 Ω
What is the maximum power that an appliance should have if it is connect to a 230V supply by a 5A cable .
46W
1.15 KW
115W
4.6 KW
The resistance of a metal wire is reduced by reducing its a. cross-sectional area b. length c. temperature
a only
c only
Resistance changes electricity to heat. Which of these appliances uses this property?
A VCR
An electric fan
A toaster
A Washing machine
In an electric motor, the energy transformation is from
electrical to chemical
electrical to mechanical
mechanical to electrical
chemical to electrical
A current of 5A is passed through a resistance of 84 Ω. Calculate the amount of heat given out by it in one minute? (J = 4.2 joules/ calories).
6000 calories
30,000 calories
500 calories
1,26,000 calories
