Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions for Physics

Doping of semiconductor is the process of ______.

It becomes possible to define potential at a point in an electric field because electric field ______.

A cube of metal is given a positive charge Q. For this system, which of the following statements is true?

From a point charge, there is a fixed point A. At A, there is an electric field of 500 V/m and potential difference of 3000 V. Distance between point charge and A will be ______.

A positively charged particle is released from rest in a uniform electric field. The electric potential energy of the charge ______.

1. The metal plate divides the capacitor into two capacitors connected in parallel to each other.
    
2. The metal plate divides the capacitors into two capacitors connected in series with each other.
    
3. The metal plate is equivalent to a dielectric of zero dielectric constant.

Assertion: A current flows in a conductor only when there is an electric field within the conductor.
Reason: The drift velocity of electron in presence of electric field decreases.

Ten identical cells connected in series are needed to heat a wire of length one meter and radius ‘r’ by 10ºC in time ‘t’. How many cells will be required to heat the wire of length two meter of the same radius by the same temperature in time ‘t’?

A hank of uninsulated wire consisting of seven and a half turns is stretched between two nails hammered into a board to which the ends of the wire are fixed. The resistance of the circuit between the nails is determined with the help of electrical measuring instruments. Determine the proportion in which the resistance will change if the wire is unwound so that the ends remain to be fixed to the nails.

Which of the following characteristics of electrons determines the current in a conductor?

Assertion: When current through a bulb decreases by 0.5%, the glow of bulb decreases by 1%.
Reason: Glow (Power) which is directly proportional to square of current.