Science (English Medium) Class 12 - CBSE Question Bank Solutions for Physics

What kind of ferromagnetic material is used for coating magnetic tapes in a cassette player, or for building ‘memory stores’ in a modern computer?

A certain region of space is to be shielded from magnetic fields. Suggest a method.

A Rowland ring of mean radius 15 cm has 3500 turns of wire wound on a ferromagnetic core of relative permeability 800. What is the magnetic field B in the core for a magnetising current of 1.2 A?

Which of the following methods can be used to charge a metal sphere positively without touching it? Select the most appropriate.

Nickel shows ferromagnetic property at room temperature. If the temperature is increased beyond curie temperature, then it will show ______.

Without the concept of displacement current it is not possible to correctly apply Ampere’s law on a path parallel to the plates of parallel plate capacitor having capacitance C in ______.

Displacement current is given by ______.

Average power supplied to a capacitor over one complete cycle is ______.

If circuit containing capacitance only, the current ______.

The propagation of light is best described by ______.

Relation between atomic number (Z), neutron number (N) and mass number (A) is ______.

The nuclei of isotopes of a given element differ from each other in their number of ______.

In n-type semiconductor, the fifth electron ______.

In n-type semiconductor majority carriers and minority carriers are respectively ______.

In p-type semiconductor, the dopant is ______.

In p-type semiconductor, ______.

The electron and hole concentration in a semiconductor in thermal equilibrium is given by ______.

The surface charge density of a thin charged disc of radius R is σ. The value of the electric field at the center of the disc is `sigma/(2∈_0)`. With respect to the field at the center, the electric field along the axis at a distance R from the center of the disc ______.