Current Electricity And Magnetostatics Mock Tests

A moving coil galvanometer has a resistance of 50 Ω and gives full scale deflection at a current of 0.01 A. To convert it into a voltmeter with a range of 0–10 V, the resistance that should be connected in series is:

The drift velocity of electrons in a copper wire is directly proportional to:

In a potentiometer experiment, a cell of emf 1.5 V gives a balancing length of 60 cm. If another cell gives a balancing length of 80 cm with the same potentiometer, the emf of the second cell is:

The magnetic field at the centre of a circular coil of radius R carrying current I is B. If the same wire is rewound as a coil of radius R/2 carrying the same current, the new magnetic field at the centre is:

Two long straight parallel wires carry currents I and 2I in the same direction and are separated by distance d. The ratio of magnetic fields at a point midway between the wires due to both wires to the field due to current I alone at that distance is:

A carbon resistor has color bands: Orange, White, Red, Gold. Its resistance value is:

A wire of resistance R is stretched to double its length. Its new resistance will be:

In a balanced Wheatstone bridge, the ratio of resistances in two adjacent arms is 2:3. If the third arm has resistance 6 Ω, the fourth arm resistance is: