MCQ
Instead of angular momentum quantisation a student gives predicts that energy is quantised as $E=\frac{-E_{\bullet}}{n},\left(E_{0}>0\right)$ and $n$ is a positive integer. Which of the following options is correct?
  • A
    The radius of the electron orbit is $r \propto \sqrt{n}$.
  • B
    The speed of the electron is $v \propto \sqrt{n}$.
  • C
    The angular speed of the electron is $\omega \propto \frac{1}{n}$.
  • The angular momentum of the electron is $L \propto \sqrt{n}$.

Answer

Correct option: D.
The angular momentum of the electron is $L \propto \sqrt{n}$.
d
$(d)$ As in a circular orbit, the electrostatic force provides the centripetal force, so

$\frac{m v^{2}}{r}=\frac{K z e^{2}}{r^{2}}$

or $\quad \frac{1}{2} m v^{2}=\frac{K z e^{2}}{2 r}= KE$

and $\quad PE =-\frac{K z e^{2}}{r}$

$\therefore$ Total energy $= KE + PE$

$=\frac{K z e^{2}}{2 r}-\frac{K z e^{2}}{r}=-\frac{1}{2} \frac{K z e^{2}}{r}$

Given, $\quad E=\frac{-E_{0}}{n}$

Comparing given equation, we get

$r \propto n$

$\text { As, } \quad KE \propto \frac{1}{r} \propto \frac{1}{n} (\because r \propto n)$

$\Rightarrow v^{2} \propto \frac{1}{n} \text { or } \quad v \propto \frac{1}{\sqrt{n}}$

$\text { Since, angular momentum, } L=m v r$

$\text { or } L \propto v r$

$\text { or } L \propto \frac{1}{\sqrt{n}} n$ $\quad(\because r \propto n)$

$\text { or } L \propto \sqrt{n}$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Similar questions

Hubble showed that the universe as a whole is expanding and the distant stars are receding from us. The spectral line from a star, when compared with the corresponding line from an source will then show
The temperature of cold junction and neutral temperature of a thermocouple are 15℃ and 280℃ respectively. The temperature of inversion is
Choose the only correct statement out of the following
The valence of an impurity added to germanium crystal in order to convert it into a $ P-$ type semi conductor is
Wave property of electrons implies that they will show diffraction effects. Davisson and Germer demonstrated this by diffracting electrons from crystals. The law governing the diffraction from a crystal is obtained by requiring that electron waves reflected from the planes of atoms in a crystal interfere constructively (see figure).

Electrons accelerated by potential $V$ are diffracted from a crystal. If $d =1\; \mathring A$, and $i =30^{\circ}$. $V$ should be about ....... $V$

$\left( h =6.6 \times 10^{-34}\; J-s , m =9.1\times 10^{-31}\; kg , e =1.610^{-19} \;C \right)$

A coil, a capacitor and an $AC$ source of $rms$ voltage $24 \,V$ are connected in  series. By varying the frequency of the source, a maximum $rms$ current of $6\,A$ is  observed. If coil is connected to a battery of $emf$ $12 \,volt$ and internal resistance $4\,\Omega$, then current through it in steady state is......$A$
The time of revolution of an electron around a nucleus of charge $Ze$ in $n^{th}$ Bohr orbit is directly proportional to
The forward biased diode connection is
A parallel plate capacitor is made of two circular plates separated by a distance $5\ mm$ and with a dielectric of dielectric constant $2.2$ between them. When the electric field in the dielectric is $3 \times 10^4$ $ Vm^{-1}$ the charge density of the positive plate will be close to
A galvanometer can be used as a voltmeter by connecting a