The specific resistance of a conductor increases with:
1. | increase in temperature. |
2. | increase in cross-section area. |
3. | increase in cross-section and decrease in length. |
4. | decrease in cross-section area. |
For a cell, the terminal potential difference is \(2.2\) V when the circuit is open and reduces to \(1.8\) V when the cell is connected to the resistance of \(R = 5~\Omega\). The internal resistance of cell (\(r\)) is:
1. | \(\dfrac{10}{9}~ \Omega\) | 2. | \(\dfrac{9}{10}~ \Omega\) |
3. | \(\dfrac{11}{9}~ \Omega\) | 4. | \(\dfrac{5}{9}~ \Omega\) |
If the specific resistance of a potentiometer wire is and the current flow through it is 0.1 A, the cross-sectional area of the wire is , then potential gradient will be:
1.
2.
3.
4.
The resistance of each arm of the wheat stone bridge is \(10~ \Omega.\) A resistance of \(10~ \Omega\) is connected in series with a galvanometer. The equivalent resistance across the battery will be:
1.\(10~ \Omega\)
2.\(15~ \Omega\)
3. \(20~ \Omega\)
4. \(40~ \Omega\)
If copper and silicon are cooled from 300 K to 60 K, then the specific resistance will:
1. Decrease in copper but increase in silicon
2. Increase in copper but decrease in silicon
3. Increase in both
4. Decrease in both
Two \(220\)-volts, \(100\)-watts bulbs are connected first in series and then in parallel. Each time the combination is connected to a \(220\)-volts AC supply line. The power drawn by the combination in each case respectively will be:
1. \(50\) watts, \(100\) watts
2. \(100\) watts, \(50\) watts
3. \(200\) watts, \(150\) watts
4. \(50\) watts, \(200\) watts
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 parallel, the time taken by the same quantity of water to boil will be:
1. \(8\) min
2. \(4\) min
3. \(25\) min
4. \(15\) min
In a Wheatstone bridge, all four arms have equal resistance \(R.\) If the resistance of the galvanometer arm is also \(R,\) the equivalent resistance of the combination is:
1. | \(R/4\) | 2. | \(R/2\) |
3. | \(R\) | 4. | \(2R\) |
A fuse wire is a wire of:
1. high resistance and high melting point
2. high resistance and low melting point
3. low resistance and low melting point
4. low resistance and high melting point
A \(6\)-volt battery is connected to the terminals of a three-metre-long wire of uniform thickness and resistance of \(100\) ohms. The difference of potential between two points on the wire separated by a distance of \(50\) cm will be:
1. \(3\) V
2. \(1\) V
3. \(1.5\) V
4. \(2\) V