When three identical bulbs of 60 watts and 200-volt rating are connected in series to a 200-volt supply, the power drawn by them will be:
1. 180 watts
2. 10 watts
3. 20 watts
4. 60 watts
The electric resistance of a particular wire of iron is R. If its length and radius are doubled, then:
1. | The resistance will be halved and the specific resistance will remain unchanged |
2. | The resistance will be halved and the specific resistance will be doubled |
3. | The resistance and the specific resistance, will both remain unchanged |
4. | The resistance will be doubled and the specific resistance will be halved |
Resistances n, each of r ohm, when connected in parallel give an equivalent resistance of R ohm. If these resistances were connected in series, the combination would have resistance in ohms, equal to:
1.
2. R/n
3. nR
4. n2 R
The current in \(8~\Omega\) resistance is (in the figure below):
1. \(0.69\) A
2. \(0.92\) A
3. \(1.30\) A
4. \(1.6\) A
If the power dissipated in 5 Ω is 20 W then the power dissipated in 4 Ω is:
1. 4 W
2. 6 W
3. 10 W
4. 20 W
The value of R for which power in it is maximum is:
1. 3 Ω
2. 6 Ω
3. 12 Ω
4. 9 Ω
The terminal potential difference of a cell is greater than its emf when:
1. | A battery of less emf is connected in its series. |
2. | A battery of higher emf is connected in its series. |
3. | A battery of higher emf is connected in its parallel. |
4. | A battery of less emf is connected in its parallel. |
In India electricity is supplied for domestic use at 220 V. It is supplied at 110 V in the USA. If the resistance of a 60 W bulb for use in India is R, the resistance of a 60 W bulb for use in the USA will be:
1. 2R
2. R/4
3. R/2
4. R
A battery is charged at a potential of \(15\) V for \(8\) hours when the current flowing is \(10\) A. The battery on discharge supplies a current of \(5\) A for \(15\) hours. The mean terminal voltage during discharges is \(14\) V. The "Watt hour" efficiency of the battery is:
1. \(80\%\)
2. \(90\%\)
3. \(87.5\%\)
4. \(82.5\%\)
Five equal resistances each of resistance \(R\) are connected as shown in the figure below. A battery of \(V\) volts is connected between \(A\) and \(B\). The current flowing in \(AFCEB\) will be:
1. \(\frac{V}{R}\)
2. \(\frac{V}{2R}\)
3. \(\frac{2V}{R}\)
4. \(\frac{3V}{R}\)