Question

Magnitude of kinetic energy in an orbit is equal to
(A) Half of the potential energy
(B) Twice of the potential energy
(C) One fourth of the potential energy
(D) None of these

Answer 1

Hint: Electrons revolve around the nucleus in orbits. The energy of an electron can be given by kinetic energy and potential energy. The sum of the kinetic energy and potential energy is equal to the total energy of an electron. These two energies are opposite to each other.

Complete Step By Step Answer:
Orbits is the path in which the electron revolves around the nucleus in an atom. Orbitals will be present in orbits. The region in which there is a maximum probability of finding an electron is known as an orbital.
The energy of an electron is given by the sum of both kinetic energy and potential energy.
The kinetic energy of an electron is given as $ \dfrac{1}{2} \times \dfrac{{Z{e^2}}}{r} $
The potential energy of an electron is given as $ \dfrac{{ - Z{e^2}}}{r} $
From the above two equations, it was clear that kinetic and potential energy are opposite to each other and kinetic energy is half of the potential energy.
Thus, the magnitude of kinetic energy in an orbit is equal to half of the potential energy.

Note:
Potential energy of an electron is always larger than the kinetic energy of an electron. But potential energy will be given in negative, whereas kinetic energy is given as positive. The potential energy of the electron decreases with the increase in the size of orbit.