KCET 2026 Physics Solved Paper

Concept:Bohr's second postulate states that the angular momentum of an electron in a permitted orbit is quantised.Explanation:According to Bohr's second postulate, an electron revolves only in those orbits where its angular momentum is an integral multiple of $\frac{h}{2\pi}$.This condition is written as:$$mvr = n\frac{h}{2\pi}$$Here, $m$ is the mass of the electron, $v$ is its speed, $r$ is the radius of the orbit, $h$ is Planck's constant, and $n = 1, 2, 3, \ldots$ is the principal quantum number.Since $n$ can take only whole-number values, the angular momentum $mvr$ cannot have any arbitrary value.It can have only fixed or discrete values, which means angular momentum is quantised.This quantisation is the direct consequence of Bohr's second postulate.Therefore, the correct option is the one that identifies angular momentum of the electron as being quantised.Answer:Option C: Angular momentum of electron.