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
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
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
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
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 potential at a point is 20 V. What is the work done to bring a charge of 0.5 C from infinity to this point.
20J
10J
5J
40J
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
The resistance across AB is
4 Ω
1Ω
2 Ω
1.5 Ω
In an electric motor, the energy transformation is from
electrical to chemical
electrical to mechanical
mechanical to electrical
chemical to electrical
Which of the following statements does not represent ohm's law?
current / potential difference = constant
potential difference / current = constant
pottential difference = Resistance × current
current = resistance x potential difference
