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 when a current is flowing in it. If both the radius and current are doubled, then the drift velocity will be:
1. | 2. | ||
3. | 4. |
1. | A | 2. | A |
3. | A | 4. | Infinite |
The current as shown in the circuit will be:
1. | 2. | ||
3. | 4. |
A meter bridge is set up to determine unknown resistance using a standard resistor. The galvanometer shows the null point when the tapping key is at a cm mark. End corrections are cm and cm respectively for end and . Then the value of is:
1.
2.
3.
4.
Which of the following graph correctly represents the variation of mobility of electrons with applied electric field in a metallic conductor?
1. | ![]() |
2. | ![]() |
3. | ![]() |
4. | ![]() |