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Recent questions tagged atoms-and-nuclei

There are two radioactive substance A and B . Decay constant of B is two times that of A . Initially both have equal no.of nuclei . After n Lay liver of A rate of disintegration of both are equal . The value of n is

asked Feb 24, 2014 by yamini.v

1 answer

If stationary proton and $\;\alpha-\;$ particle dre accelerated through same potential difference , the ratio of Debrogle's wavelength will be

asked Feb 24, 2014 by yamini.v

1 answer

The wavelength of $\;K_{\alpha}\;$ X-ray produced by X-ray to be is 0.76$A^{0}\;$. The atomic no.of anticathode material is

asked Feb 24, 2014 by yamini.v

1 answer

Radio isotopes of phosphorous $\;P^{32}\;$ and $\;P^{35}\;$ are mixed in ratio of 2:1 of atoms .The activity of samples 2 $\;\mu Ci\;$.Find activity of sample after 30 days. $\;t_{\large\frac{1}{2}}\;$ of $\;P^{32}=14\;$days and $\;t_{\large\frac{1}{2}}\;$ of $\;P^{33}\;$ is 25 days.

asked Feb 24, 2014 by yamini.v

1 answer

The mean lives of an radio active substance are 1620 and 405 years for $\;\alpha-\;$emission and $\;\beta-\;$ emission respee. Find out time during which three fourth of a sample will decay if it is decaying both the $\;\alpha-\;$emission and $\;\beta-\;$ emission simultaneously

asked Feb 24, 2014 by yamini.v

1 answer

It is proposed to use nuclear fusion reaction : $\; _{1}H^{2}+_{1}H^{2}=\;_{2}He^{4}\;$ in a nuclear reactor of 200MW rating . If energy from above reaction is used with a $\;25 \%\;$ efficiency in reactor how many gr ams of deuterium will be needed per day . (The masses of $\;_{1}H^{2}\;$ and $\;_{2}He^{4}\;$ are 2.0141 & 4.0026 amu respectively

asked Feb 24, 2014 by yamini.v

1 answer

uranium ores on earth at present time typically have a composition of $\;99.3 \%$ of isotope $\;_{92}U^{238}\;$ and $\;0.7 \%\;$ of isotope $\;_{92}U^{235}\;$. The half lives of these isotopes are $\;4.47 \times10^{9}y\;$ and $\;7.04\times10^{8}y\;$ respectively . If these isotopes were equally abundent when the earth was formed , estimate the age of earth .

asked Feb 24, 2014 by yamini.v

1 answer

How much energy must a bombarding proton possess to cause the reaction ? $\;^{7}H_{3}+^{1}H_{1} \to _{4} Be^{7}+_{0}n^{1}$

asked Feb 23, 2014 by yamini.v

1 answer

The binding energy of $\;_{17}cl^{35}\;$ nucleus is 298 HeV . Find its atomic mass $\;(_{1}H^{1})\;$ is 1.008143 a.m.u and that of a neutron is 1.008986 a.m.u . Given $\;1amu=931 MeV\;$

asked Feb 23, 2014 by yamini.v

1 answer

Where $\;0.5 A^{0}\;$ x-rays strike a material , the photoelectrons from K shell are observed to move in a circle of radius 23mm in a magnetic fields of $\;2\times10^{-2}T\;.$ Than the binding energy of K-shell electrons is

asked Feb 23, 2014 by yamini.v

1 answer

If the $\;K_{\alpha}\;$ radiation of $\;M_{0}\;(Z=42)\;$ has a wavelength of $\;0.71 A^{0}\;$ , than the wavelength of corresponding radiation of Cu , i. e , $\;K_{\alpha}$ for Cu $\;(z=29)\;$ assuming $\;\sigma=1\;$ .

asked Feb 22, 2014 by yamini.v

1 answer

A perfectly reflecting solid sphere of radius r is kept in the path of a parallel beam of light of large aperture . If the beam carries an intensity I find force exerted by beam on sphere .

asked Feb 22, 2014 by yamini.v

1 answer

A plate of mass 10gm is in equilibrium in air due to force exerted by light beam on plate . Assuming plate is perfectly absorbing the power of beam is :

asked Feb 22, 2014 by yamini.v

1 answer

Light described at a place by the equation $\;\varepsilon=(100 V/m)\;[sin(5\times10^{15} s^{-1})t+sin(8 \times10^{15})t]\;$ falls on a metal surface having work function 2eV . Than maximum kinetic energy of photo electrons will be :

asked Feb 22, 2014 by yamini.v

1 answer

A photocell is operating in saturation mode with a aphotocurrent 4.8mA when a monochromatic radiation of wavelength $\;3000A^{0}\;$ and power 1mW is incident. When another monochromatic radiation of wavelength $\;1650A^{0}\;$ and power 5mW is incident , it is observed that maximum velocity of photoelectron generation per incident to be same for both cases . Than the threshold wavelength for cell is : Find saturation current in second case

asked Feb 22, 2014 by yamini.v

1 answer

A photocell is operating in saturation mode with a aphotocurrent 4.8mA when a monochromatic radiation of wavelength $\;3000A^{0}\;$ and power 1mW is incident. When another monochromatic radiation of wavelength $\;1650A^{0}\;$ and power 5mW is incident , it is observed that maximum velocity of photoelectron generation per incident to be same for both cases . Than the threshold wavelength for cell is : The efficiency of photoelectron generation will be

asked Feb 22, 2014 by yamini.v

1 answer

A photocell is operating in saturation mode with a aphotocurrent 4.8mA when a monochromatic radiation of wavelength $\;3000A^{0}\;$ and power 1mW is incident. When another monochromatic radiation of wavelength $\;1650A^{0}\;$ and power 5mW is incident , it is observed that maximum velocity of photoelectron generation per incident to be same for both cases . Than the threshold wavelength for cell is :

asked Feb 22, 2014 by yamini.v

1 answer

A small potassium foil is placed (perpendicular to direction of incidence of light ) a distance r (=0.5 m) from a point light source whose output power $\;P_{0}\;$ is 1W . Assuming wave nature of light . how long would it take for foil to soak up enough energy (=1.8eV) from the beam to eject on electron ? (Assume that ejected photoelectron collected its energy from a circular area of foil whose radius equals radius of potassium atom ($\;1.3\times10^{-10}m$))

asked Feb 22, 2014 by yamini.v

1 answer

A beam of light consists of 4 wavelength $\;4000A^{0},4800A^{0},6000A^{0}\; and\;7000A^{0}\;,$ each of intensity $\;1.5\times10^{-3}Wm^{-2}\;.$The beam falls normally on an area $\;10^{-4} m^2\;$ of a clean metallic surface of work function 1.9eV . Assuming no loss of light energy the no.of photoelectrons liberated per second is

asked Feb 22, 2014 by yamini.v

1 answer

In an experiment on photo electric emission , following observations were made ; (1) Wavelength of incident light = $\;1.98\times10^{-7}m\;$ 2 Stopping potential = $\;2.5 volt\;$. Then kinetic energy of photoelectrons with maximum speed and Thus hold frequency are respectively

asked Feb 22, 2014 by yamini.v

1 answer

A small particle of mass m moves in such a way that the potential energy $\;u=ar^2\;$ where a is a constant and r is the distance of particle from origin. Assuming Bohr's model of quantization of angular momentum and circular orbits. Then the radium of $\;n^{th}\;$ allowed orbit is

asked Feb 22, 2014 by yamini.v

1 answer

In a transition to a state of excitation energy 10.19eV , a hydrogen atom emits a $\;4890 A^{0}\;$ photon . Then the binding energy of initial state is :

asked Feb 22, 2014 by yamini.v

1 answer

A single electron orbits around a stationary nucleus of charge +ze , where z is a constant and e is magnitude of electronic charge. It requires 47.2eV to exite the electron from $\;2^{nd}\;$ Bohr orbital to $\;3^{rd}\;$ Bohr orbital. find the atomic no.of element.The wavelength of radiation required remove electron from first Bohr's orbit to infinity is

asked Feb 22, 2014 by yamini.v

1 answer

A single electron orbits around a stationary nucleus of charge +ze , where z is a constant and e is magnitude of electronic charge. It requires 47.2eV to exite the electron from $\;2^{nd}\;$ Bohr orbital to $\;3^{rd}\;$ Bohr orbital. find the atomic no.of element.

asked Feb 22, 2014 by yamini.v

1 answer

Electrons of energies 12.09 eV can cause radiation to be emitted from hydrogen atom. calculate the principal quantum number of the orbit to which the electron in the hydrogen atom is raised and the wavelength of radiation emitted if it drops back to the ground state .

asked Feb 21, 2014 by yamini.v

1 answer

The energy of an electron in an excited hydrogen atom is $\;-3.4 e V \;.$ Calculate the angular momentum of electron according to Bor's theorey. Plan ck's constant h= $\;6.626\times10^{-34} J-s\;.$

asked Feb 21, 2014 by yamini.v

1 answer

The orbital magnetic dipole moment of electron in hydrogen atom is

asked Feb 21, 2014 by yamini.v

1 answer

Find the ratio of De-Broglie wavelength of molecules of hydrogen and helium which are at temperatures $\;27^{0} C \;and\; 127^{0} C \;$ respectively

asked Feb 21, 2014 by yamini.v

1 answer

An electron is accelerated by a potential difference of 50 Volt ., then the de-Broglie wavelength associated with it .

asked Feb 21, 2014 by yamini.v

1 answer

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