Three equal resistors connected in series across a source of emf together dissipate 10 W of power. What will be the power dissipated in watt if the same resistors are connected in parallel across the same source of emf ?
W
10W
30W
90W
In metre-bridge the balancing length from left is found to be 20 cm when standard resistance of is in right gap. The value of unknown resistance is
Two bulbs 25 W, 220 V and 100 W, 220 V are given, Which has higher resistance ?
25 W bulb
100 W bulb
Both bulbs will have equal resistance
Resistance of bulbs cannot be compared
A piece of copper and another of germanium are cooled from room temperature to 80K.The resistance of
each of them increases
each of them decreases
copper increases and germanium decreases
copper decreases and germanium increases
The negative Zn pole of a Daniell cell, sending a contant current through a circuit, decreases in mass by 0.13 g in 30 minutes. If the electrochemical equivalent of Zn and Cu are 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is
0.180 g
0.141 g
0.126 g
0.242 g
Two batteries of emf 4V and 8V with internal resistance are connected in a circuit with a resistance of as shown in figure. The current and potential difference between the point P and Q are
