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. | \(\dfrac{5}{3}~\text{A}\) |
A meter bridge is set up to determine unknown resistance \(x\) using a standard \(10~\Omega\) resistor. The galvanometer shows the null point when the tapping key is at a \(52\) cm mark. End corrections are \(1\) cm and \(2\) cm respectively for end \(A\) and \(B\). Then the value of \(x\) is:
1. \(10.2~\Omega\)
2. \(10.6~\Omega\)
3. \(10.8~\Omega\)
4. \(11.1~\Omega\)
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. |