Current Electricity

Related Questions

• There are three voltmeters of the same range but of resistances $10000\,\Omega $, $8000\,\Omega $ and $4000\,\Omega $ respectively. The best voltmeter among these is the one whose resistance is

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• A heating coil can heat the water of a vessel from $20^\circ C$ to $60^\circ C$ in 30 minutes. Two such heating coils are put in series and then used to heat the same amount of water through the same temperature range. The time taken now will be (neglecting thermal capacity of the coils)

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• In an experiment to measure the internal resistance of a cell by potentiometer, it is found that the balance point is at a length of 2m when the cell is shunted by a $5\,\Omega $ resistance; and is at a length of 3m when the cell is shunted by a $10\,\Omega $ resistance. The internal resistance of the cell is, then

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• An ammeter gives full deflection when a current of 2 amp. flows through it. The resistance of ammeter is 12 ohms. If the same ammeter is to be used for measuring a maximum current of 5 amp., then the ammeter must be connected with a resistance of

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• A wire when connected to 220V mains supply has power dissipation ${P_1}$. Now the wire is cut into two equal pieces which are connected in parallel to the same supply. Power dissipation in this case is ${P_2}$. Then ${P_2}:{P_1}$ is

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