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Recent questions tagged physics
Questions
What would be the radius of second orbit of $He^{+}$ ion ?
cbse
class12
physics
ch12
sec-a
additional
easy
asked
Jul 8, 2016
by
meena.p
1
answer
The size of the atom is proportional to
cbse
class12
physics
ch12
sec-a
additional
easy
asked
Jul 8, 2016
by
meena.p
1
answer
An electron makes a transition from orbit $n=4$ to the orbit n=2 of a hydrogen atom. What is the wave length of the emitted radiation? (R= Rydberg's constant}
cbse
class12
physics
ch12
sec-b
additional
easy
asked
Jul 8, 2016
by
meena.p
1
answer
An electron is moving round the nucleus of a hydrogen atom in a circular orbit of radius r. The coulomb force $\overrightarrow{F}$ between the two is :
cbse
class12
physics
ch12
sec-a
additional
easy
asked
Jul 8, 2016
by
meena.p
1
answer
Hydrogen atoms are excited from ground state to the state of principle quantum number 4, Then the no of spectral lines observed will be
cbse
class12
physics
ch12
sec-a
additional
easy
asked
Jul 8, 2016
by
meena.p
1
answer
Name the spectral series of hydrogen spectrum lying in the infrared region .
cbse
class12
physics
ch12
sec-a
additional
easy
asked
Jul 8, 2016
by
meena.p
1
answer
How much is the radius of Bohr's innermost orbit ?
cbse
class12
physics
ch12
sec-a
additional
easy
asked
Jul 8, 2016
by
meena.p
1
answer
Write an empirical relation for parchen series lies of hydrogen spectrum
cbse
class12
physics
ch12
sec-a
additional
easy
asked
Jul 8, 2016
by
meena.p
1
answer
What is the angle of scattering for zero impact parameter ?
cbse
class12
physics
ch12
sec-a
additional
easy
asked
Jul 8, 2016
by
meena.p
1
answer
Name the series of hydrogen spectrum which has least wave length
cbse
class12
physics
ch12
sec-a
additional
easy
asked
Jul 8, 2016
by
meena.p
1
answer
When is $H_{\alpha}$ line of the Balmer series in the emission spectrum of hydrogen atom obtained ?
cbse
class12
physics
ch12
sec-a
exemplar
medium
asked
Jul 8, 2016
by
meena.p
1
answer
In which series of hydrogen spectrum , the transition involve the largest changes of energy ?
cbse
class12
physics
ch12
sec-b
exemplar
easy
asked
Jul 8, 2016
by
meena.p
1
answer
The energy of an electron in an excited hydrogen atom is $-3.4 \;ev$ calculate the angular momentum of the electron according to Bohr's theory .
cbse
class12
physics
ch12
sec-b
additional
difficult
asked
Jul 8, 2016
by
meena.p
1
answer
When electron falls from a higher energy to a lower energy level , the difference in the energies appear in the form of electromagnetic radiation . Why cannot it be emitted as other form of energy?
cbse
class12
physics
ch12
sec-a
exemplar
easy
asked
Jul 8, 2016
by
meena.p
1
answer
The mass of a H- atom is less than the sum of the mass of a proton and electron , why is this ?
cbse
class12
physics
ch12
sec-a
exemplar
medium
asked
Jul 8, 2016
by
meena.p
1
answer
The simple Bohr model is not applicable to $_2He^4$ atom because
cbse
class12
physics
ch12
sec-a
exemplar
medium
asked
Jul 8, 2016
by
meena.p
1
answer
Let $E_n=\large\frac{-1me^4}{8\in_0^2 n^2h^2}$ be the energy of the nth level of H- atom . If all the H- atoms are in the ground state and radiation of frequency $(E_2-E_1) /h$ falls on it ,
cbse
class12
physics
ch12
sec-a
exemplar
medium
asked
Jul 8, 2016
by
meena.p
1
answer
The Balmer series for the H- atom can be observed
cbse
class12
physics
ch12
sec-a
exemplar
easy
asked
Jul 8, 2016
by
meena.p
1
answer
The Bohr model for the Spectra of a H-atom
cbse
class12
physics
ch12
sec-a
exemplar
easy
asked
Jul 8, 2016
by
meena.p
1
answer
Consider aiming a beam of free electron towards free protons. when they scatter , an electron and a proton cannot combine to produce a H-atom .
cbse
class12
physics
ch12
sec-a
exemplar
medium
asked
Jul 8, 2016
by
meena.p
1
answer
An ionized H- molecules consists of an electron and two protons. The proton are separated by a small distance of the order of any strom .In the ground state ,
cbse
class12
physics
ch12
sec-a
exemplar
medium
asked
Jul 7, 2016
by
meena.p
1
answer
A set of atoms in an excited state decays
cbse
class12
physics
ch12
sec-a
exemplar
easy
asked
Jul 7, 2016
by
meena.p
1
answer
Two H atoms in the ground state collide inelastically . The maximum amount by which their combined kinetic energy is reduced is
cbse
class12
physics
ch12
sec-a
exemplar
medium
asked
Jul 7, 2016
by
meena.p
1
answer
$O_2$ molecules consists of two oxygen atoms. In the molecule , nuclear force between the nuclei of the two atoms
cbse
class12
physics
ch12
sec-a
exemplar
medium
asked
Jul 7, 2016
by
meena.p
1
answer
For the ground state, the electron in th H- atom has an angular momentum = h , according to the simple Bohr model. Angular momentum is a vector and hence there will be infinitely many orbits with the vector pointing in all possible direction . In actuality this is not true.
cbse
class12
physics
ch12
sec-a
exemplar
medium
asked
Jul 7, 2016
by
meena.p
1
answer
The Simple Bohr model cannot be directly applied to calculate the energy levels of an atom with many electrons . This is because
cbse
class12
physics
ch12
sec-a
exemplar
easy
asked
Jul 7, 2016
by
meena.p
1
answer
The binding energy of a H-atom , considering an electron moving around a fixed nuclei is $B= \large\frac{-me^4}{8n^2\in_0 h^2}$If one decides to work in a frame of reference where the electron is at rest , the proton would be around it. By similar arguments, the binding energy would be , $B=\large\frac{-Me^4}{8n^2\in_0^2h^2}$ This last expression is not correct because ,
cbse
class12
physics
ch12
sec-a
exemplar
medium
asked
Jul 6, 2016
by
meena.p
1
answer
Taking the Bohr radius as $a_0 = 53 \;pm, $ the radius of $Li^{++}$ ion in its ground state , on the basic of Bohr's model will be about
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 6, 2016
by
meena.p
1
answer
The total energy of electron in the first electron state of hydrogen atom is about $-3.4\;ev$ What is the kinetic energy of electron in this state ?
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 6, 2016
by
meena.p
1
answer
Is the average angle of deflection of $ \alpha$ particles by a thin gold foil predicted by Thomson's model much less , about the same or much greater than that predicted by Rutherford's atom model ?
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 6, 2016
by
meena.p
1
answer
In accordance with the Bohr's model find the quantum number that characterizes the earth revolution around the sun in an earth orbit of radius $1.5 \times 10^{11}\;m$ with orbital speed $3 \times 10^4 \;ms^{-1}$
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 6, 2016
by
meena.p
1
answer
A $12.5\;ev$ electron beam is used to bombard gaseous hydrogen at room temperature .What series of wave length will be emitted ?
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 6, 2016
by
meena.p
1
answer
The radius of inner most electron orbit of a hydrogen atom is $5.3 \times 10^{-11}\;m $ what are the radii of $n=2$ and $n=3$ orbits?
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 6, 2016
by
meena.p
1
answer
Using Bohr's model , calculate the orbital period of the electron in a hydrogen atom in the $n= 1,2$ and $3$ levels
cbse
class12
physics
ch12
sec-c
ncert
easy
asked
Jul 6, 2016
by
meena.p
1
answer
Using the Bohr's model , calculate the speed of the electron in a hydrogen atom in the $n= 1,2$ and 3 levels
cbse
class12
physics
ch12
sec-b
ncert
easy
asked
Jul 6, 2016
by
meena.p
1
answer
A hydrogen atom initially in the ground level absorbs a photon, which excites it to $n=4$ level. Determine the wave length and frequency of photon .
cbse
class12
physics
ch12
sec-b
ncert
medium
asked
Jul 6, 2016
by
meena.p
1
answer
The ground state energy of hydrogen atom is $-13.6 ev$ what are the kinetic and potential energies of the electron of the electron in this state ?
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 5, 2016
by
meena.p
1
answer
A difference of $2.3 \;ev$ separates two energy levels in an atom. What is the frequency of radiation emitted when the atom transmit from the upper level to the lower level .
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 5, 2016
by
meena.p
1
answer
What is the shortest wave length present in the paschen series of spectral lines ?
cbse
class12
physics
ch12
sec-b
ncert
medium
asked
Jul 5, 2016
by
meena.p
1
answer
Suppose you are given a chance to repeat the alpha particle scattering experiment using a thin sheet of solid hydrogen in place of gold foil (hydrogen is a solid at temperature below 14 k) What results do you except ?
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 5, 2016
by
meena.p
1
answer
The positively charged part of the atom possesses most of the mass of the atom in __________
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 5, 2016
by
meena.p
1
answer
An atom has a nearly continuous mass distribution in ________ but has a highly non uniform mass distribution in ____________
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 5, 2016
by
meena.p
1
answer
A classical atom based on _________ is doomed to collapse
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 5, 2016
by
meena.p
1
answer
In the ground state of __________ electrons are in stable equilibrium , while in ________ electrons always experience a net force
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 5, 2016
by
meena.p
1
answer
The size of the atom in Thomson's model is __________ the atomic size in Rutherford's model
cbse
class12
physics
ch12
sec-a
ncert
easy
asked
Jul 5, 2016
by
meena.p
1
answer
A photo cell is illuminated by a source of light , which is placed at a distance d. If distance becomes $\large\frac{d}{2}$ then the number of electrons emitted per second will be
cbse
class12
physics
ch11
sec-a
additional
easy
asked
Jul 5, 2016
by
meena.p
1
answer
Red light , how ever bright it is , cannot produce the emission of electrons from a clean zinc surface , But even weak ultra violet radiation can do so why ?
cbse
class12
physics
ch11
sec-a
additional
medium
asked
Jul 5, 2016
by
meena.p
1
answer
An electron and a proton each have de-Broglie wave length of $1.00 nm$ . What is the ratio of their linear momenta
cbse
class12
physics
ch11
sec-a
additional
easy
asked
Jul 5, 2016
by
meena.p
1
answer
The wave length of $1kev$ photon is $1.24 \times 10^{-9}\;m$. What is the frequency of $1Mev$ photon ?
cbse
class12
physics
ch11
sec-a
additional
easy
asked
Jul 5, 2016
by
meena.p
1
answer
Three particles having charges in the ratio of $2:3:5$ produce the same point on the photographic film in Thomson experiment . Their masses are in the ratio of
cbse
class12
physics
ch11
sec-a
additional
easy
asked
Jul 5, 2016
by
meena.p
1
answer
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