Current Electricity

The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then

Five equal resistances each of resistances R are connected as shown in the figure. A battery of V volts is connected between A and B. The current flowing in AFCEB will be

A 6 volt battery is connected to the terminals of a three metre long wire of uniform thickness and resistance of 100 ohm. The difference of potential between two points on the wire separated by a distance of 50 cm will be

In a Wheatstone's bridge all the four arms have equal resistance R. If the resistance of the galvanometer arm is also R, the equivalent resistance of the combination as seen by the battery is

An electric kettle has two heating coils. When one of the coils is connected to an a.c. source, the water in the kettle boils in 10 minutes. When the other coil is used the water boils in 40 minutes. If both the coils are connected in paral...

Fuse wire is a wire of

Two 220 volt, 100 watt bulbs are connected first in series and then in parallel. Each time the combination is connected to a 220 volt a.c. supply line. The power drawn by the combination in each case respectively will be

For a cell terminal potential difference is 2.2V when circuit is open and reduce to 1.8 V when cell is connected to a resistance of R = 5 \(\Omega\). Determine internal resistance of cell (r)

Specific resistance of a conductor increases with

The resistance of each arm of the Wheatstone's bridge is 10 ohm. A resistance of 10 ohm is connected in series with a galvanometer then the equivalent resistance across the battery will be

Copper and silicon is cooled from 300 K to 60 K , the specific resistance

If specific resistance of a potentiometer wire is 10-7\(\Omega\) m and current flow through it is 0.1 amp., cross-sectional area of wire is 10\(-\)6 m2 then potential gradient will be

The potentiometer is best for measuring voltage, as

The net resistance of the circuit between A and B is

A car battery of emf 12 V and internal resistance \(5 \times {10^{ - 2}}\) \(\Omega\)., receives a current of 60 amp, from external source, then terminal potential difference of battery is

Two bulbs of (40 W, 200 V), and (100 W, 200 V). Then correct relation for their resistances