Question
When a hydrogen atom emits a photon of energy $12.09 \,eV$, its orbital angular momentum changes by (where $h$ is Planck's constant)
✓
Answer
(c)
This is the case of electron jumping from $3^{\text {rd }}$ orbit to $1^{\text {st }}$ orbit
$\Delta L=\frac{n_1 h}{2 \pi}-\frac{n h}{2 \pi}$
$=\frac{3 h}{2 \pi}-\frac{h}{2 \pi}=\frac{h}{\pi}$
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Force acting upon a charged particle kept between the plates of a charged condenser is $F$. If one plate of the condenser is removed, then the force acting on the same particle will become
→Two parallel beams of electrons moving in the same direction produce a mutual force
The adiabatic elasticity of a diatomic gas at $NTP$ is ........ $N / m ^2$
→Two identical conducting spheres, having charges of opposite sign, attract each other with a force of $0.108$ $N$ when separated by $0.5$ $m$. The spheres are connected by a conducting wire, which is then removed, and thereafter, they repel each other with a force of $ 0.036$ $N$. The initial charges on the spheres are
→The intensity of light from a continuously emitting laser source operating at $638 \,nm$ wavelength is modulated at $1 \,GHz$. The modulation is done by momentarily cutting the intensity off with a frequency of $1 \,GHz$. What is the farthest distance apart two detectors can be placed in the line of the laser light, so that they can see the portions of the same pulse simultaneously?
→(Consider the speed of light in air $3 \times 10^{8} \,m / s$ )
The metallic bob of a simple pendulum has the relative density $\rho$. The time period of this pendulum is $T$. If the metallic bob is immersed in water, then the new time period is given by
→A region surrounding a stationary electric dipoles has
Two spheres $P$ and $Q$ of equal masses are attached to a string of length $2\,\, m$ as shown in figure. The string and the spheres are then whirled in a horizontal circle about $O$ at a constant rate. What is the value of the ratio
$\left( {\frac{{{\text{Tension in the string between P and Q}}}}{{{\text{Tension in the string between P and O}}}}} \right)?$
→$\left( {\frac{{{\text{Tension in the string between P and Q}}}}{{{\text{Tension in the string between P and O}}}}} \right)?$
Aball is thrown vertically down with velocity of $5m/s$. With what velocity should another ball be thrown down after $2$ seconds so that it can hit the $1^{st}$ ball in $2$ seconds.........$m/s$
→A block of mass $m$ is on an inclined plane of angle $\theta$. The coefficient of friction between the block and the plane is $\mu$ and $\tan \theta>\mu$. The block is held stationary by applying a force $\mathrm{P}$ parallel to the plane. The direction of force pointing up the plane is taken to be positive. As $\mathrm{P}$ is varied from $\mathrm{P}_1=$ $m g(\sin \theta-\mu \cos \theta)$ to $P_2=m g(\sin \theta+\mu \cos \theta)$, the frictional force $f$ versus $P$ graph will look like
→