If a resistance coil is made by joining in parallel two resistances each of 20. An emf of 2V is applied across this coil for 100 seconds. The heat produced in the coil is
(1) 20 J
(2) 10 J
(3) 40 J
(4) 80 J
Which of the following graph correctly represents the variation of mobility \((\mu)\) of electrons with applied electric field \((E)\) in a metallic conductor?
1. | 2. | ||
3. | 4. |
If I be the current limit of a fuse wire of length l and radius r, then select the appropriate relation
(1)
(2)
(3)
(4)
The resistance of platinum wire at 0 is 22.05 and at 100 it becomes 22.70 . When the wire is heated to a temperature of t the resistance of wire becomes 24.91. The value of t is
1. 220
2. 440
3. 310
4. 550
The sensitivity of a potentiometer can be increased by
1. increasing the potential gradient
2. decreasing the length of potentiometer wire
3. decreasing the current in the potentiometer wire
4. all of these
A current of 1 mA is flowing through a copper wire. How many electrons will pass a given point in one second
1.
2.
3.
4.
The drift velocity of free electrons in a conductor is \(v\) when a current \(i\) is flowing in it. If both the radius and current are doubled, then the drift velocity will be:
1. | \(v\) | 2. | \(\dfrac{v}{2}\) |
3. | \(\dfrac{v}{4}\) | 4. | \(\dfrac{v}{8}\) |
1. | \(1\) A | 2. | \(2\) A |
3. | \(4\) A | 4. | Infinite |
The current \(I\) as shown in the circuit will be:
1. | \(10~\text{A}\) | 2. | \(\dfrac{20}{3}~\text{A}\) |
3. | \(\dfrac{2}{3}~\text{A}\) | 4. | \(\dfrac{5}{3}~\text{A}\) |