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
The resistance of a metal wire is reduced by reducing its a. cross-sectional area b. length c. temperature
a and b only
b and c only
a only
c only
In the circuit shown the bulb marked 2R has twice the resistance of the bulb marked R. Compared with bulb 2R, the current in bulb R and its brightness compared to the other bulb, is
Larger current in R brighter 2R
Larger current in R dimmer 2R
Smaller current in R brighter 2R
Smaller current in R dimmer 2R
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 c only
The resistance across AB is
4 Ω
1Ω
2 Ω
1.5 Ω
A 6 V battery is made up of four 1.5 V cells, each with an internal resistance of 0.2 ohms connected in series. The greatest current that could possibly be obtained from such a battery is
0.3A
0.75A
30A
7.5A
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
Find the time required to deposit electrolytically 2 gm of gold by passing a current of 2 A. The e.c.e.of gold is 0.0006812 gm/coulomb.
14.68 min
13.64 sec
7.8 min
