Q. An electron in hydrogen atom first jumps from second excited state to first excited state and then from first excited state to ground state. Let the ratio of wavelength, momentum and energy of photons emitted in these two cases be, $a, b$ and $c$ respectively. Then :

Atoms Report Error

A

$c=\frac{1}{a}$

B

$a=9 / 4$

C

$b=5 / 27$

D

$c=5 / 27$

Solution:

Wavelenths emitted in the two cases are
$\lambda_{21}=\frac{\lambda_{32}}{\lambda_{21}} \text { and } l_{32}=\frac{12431}{1.89\, e V}$
$a=\frac{\lambda_{32}}{\lambda_{21}}=\frac{10.2}{1.89}=\frac{27}{5}$
Momentum ratio of photons is
$b=\frac{\lambda / \lambda_{32}}{\lambda / \lambda_{21}}=\frac{5}{27}$
Energy ratio of photons is
$c=\frac{h c / \lambda_{32}}{h c / \lambda_{21}}=\frac{5}{27}=\frac{1}{a}$

Questions from Atoms

1. Pick out the statement which is true

KCET 2001

2. "Plum pudding" model of an atom was proposed by

COMEDK 2012

3. The transition from the state $n = 4$ to $n = 3$ in a hydrogen like atom results in ultraviolet radiation. Infrared radiation will be obtained in the transition from

AIEEE 2009

4. Muon $ (\mu^{-})$ is a negatively charged $(|q | = |e|$ particle with a mass $m_{\mu} = 200$ me, where me is the mass of the electron and e is the electronic charge. If $\mu$- is bound to a proton to form a hydrogen like atom, identify the correct statements.
(A) Radius of the muonic orbit is $200$ times smaller than that of the electron.
(B) The speed of the $\mu^{-}$ in the $n^{th}$ orbit is $\frac{1}{200}$ times that of the electron in the $n^{th}$ orbit.
(C) The ionization energy of muonic atom is $200$ times more than that of an hydrogen atom.
(D) The momentum of the muon in the $n^{th}$ orbit is $200 $ times more than that of the electron.

JEE Main 2018

5. The ratio of the wavelengths for $2 \rightarrow 1$ transition in $Li^{2 +}, \, \text{He}^{+}$ and $H$ is

NTA Abhyas 2020

Physics Most Viewed Questions

1. If $E$ and $G$ respectively denote energy and gravitational constant, then $\frac{ E }{ G }$ has the dimensions of:

NEET 2021 Physical World, Units and Measurements

2. The de Broglie wavelength of an electron moving with kinetic energy of $144 \,eV$ is nearly

NEET 2020 Dual Nature of Radiation and Matter

3. A car starts from rest and accelerates at $5\, m / s ^{2}$ At $t=4\, s$, a ball is dropped out of a window by a person sitting in the car. What is the velocity and acceleration of the ball at $t =6\, s$ ? (Take $\left. g =10\, m / s ^{2}\right)$

NEET 2021 Motion in a Straight Line

4. A wheel with $20$ metallic spokes each $1\, m$ long is rotated with a speed of $120\, rpm$ in a plane perpendicular to a magnetic field of $0.4\, G$. The induced emf between the axle and rim of the wheel will be, $(1 G = 10^{-4}\, T)$

NEET 2020 Electromagnetic Induction

5. A barometer is constructed using a liquid (density $= 760 \,kg/m^{3})$ What would be the height of the liquid column, when a mercury barometer reads $76\, cm$ ?
(density of mercury $= 13600 kg/m^{3})$

NEET 2020 Mechanical Properties of Fluids