In the Study of Geiger-marsdon Experiment on Scattering of α Particles by a Thin Foil of Gold, Draw the Trajectory of α-particles in the Coulomb Field of Target Nucleus. Explain Briefly How One Gets the Information on the Size of the Nucleus from this Study. - Physics


In the study of Geiger-Marsdon experiment on scattering of α particles by a thin foil of gold, draw the trajectory of α-particles in the coulomb field of target nucleus. Explain briefly how one gets the information on the size of the nucleus from this study.

From the relation R = R0 A1/3, where R0 is constant and A is the mass number of the nucleus, show that nuclear matter density is independent of A



 Trajectory of α Particles in Coulomb Field of Target Nucleus

From this experiment, the following is observed:
1. Most of the alpha particles pass straight through the gold foil. It means that they do not suffer any collision with gold atoms.

2. About one alpha particle in every 8000 alpha particles deflects by more than 90°

As most of the alpha particles go undeflected and only a few get deflected, this shows that most of the space in an atom is empty and at the centre of the atom, there exists a nucleus. By the number of the alpha particles deflected, the information regarding size of the nucleus can be known.

If m is the average mass of a nucleon and R is the nuclear radius, then mass of nucleus = mA, where A is the mass number of the element.

Volume of the nucleus`V=4/3piR^3`



Density of nuclear matter`rho=(mA)/V`



This shows that the nuclear density is independent of A

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2014-2015 (March) Delhi Set 2


Obtain approximately the ratio of the nuclear radii of the gold isotope `""_97^197 "Au"` and the silver isotope `""_47^197"Ag"`.

The nucleus `""_10^23"Ne"` decays by `beta^(-)`emission. Write down the β decay equation and determine the maximum kinetic energy of the electrons emitted. Given that:

`"m"(""_10^23 "Ne")` = 22.994466 u

`"m"(""_11^23 "Na")` = 22.989770 u.

In a periodic table the average atomic mass of magnesium is given as 24.312 u. The average value is based on their relative natural abundance on earth. The three isotopes and their masses are `""_12^24Mg` (23.98504u),  `""_12^25 Mg` (24.98584u) and `""_12^26Mg` (25.98259u). The natural abundance of `""_12^24 Mg` is 78.99% by mass. Calculate the abundances of other two isotopes.

What do you mean by polar molecules and non-polar molecules? Give ‘one’ example each.

Name a material which is used in making control rods in a nuclear reactor.

Write one balanced equation to show Emission of `beta^-` (i.e. a negative beta particle)

With the help of a suitable example and an equation, explain the term pair production.

Two nuclei have mass numbers in the ratio 1: 2. What is the ratio of their nuclear densities?

If neutrons exert only attractive force, why don't we have a nucleus containing neutrons alone?

The mass number of a nucleus is

Potassium-40 can decay in three modes. It can decay by β-emission, B*-emission of electron capture. (a) Write the equations showing the end products. (b) Find the Q-values in each of the three cases. Atomic masses of `""_18^40Ar` , `""_19^40K` and `""_20^40Ca` are 39.9624 u, 39.9640 u and 39.9626 u respectively.

(Use Mass of proton mp = 1.007276 u, Mass of `""_1^1"H"` atom = 1.007825 u, Mass of neutron mn = 1.008665 u, Mass of electron = 0.0005486 u ≈ 511 keV/c2,1 u = 931 MeV/c2.)

The atomic mass of Uranium `""_92^238"U"` is 238.0508 u, while that of Thorium `""_90^234"Th"` is 234.0436u, and that of Helium `""_2^4"He"` "is 4.0026u. Alpha decay converts `""_92^238"U"` into `""_92^234"Th"` as, shown below:

`""_92^238"U" -> ( ""_90^234"Th" + ""_2^4"He" + "Energy" )`

What is a neutrino?

Find the Q-value and the kinetic energy of the emitted α-particle in the α-decay of `""_86^220"Rn"`.

Given `"m"(""_88^226"Ra")` = 226.02540 u, `"m"(""_86^222 "Rn")` = 222.01750 u, 

`"m"(""_86^220 "Rn")`= 220.01137 u, `"m"(""_84^216 "Po")`= 216.00189 u.

All nuclides with same mass number A are called ______.

Nuclides with same neutron number N but different atomic number Z are called ______.

A vessel contains oil (density 0.8 g/cm3) over mercury (density 13.6 g/cm3). A sphere of homogeneous composition floats with half its volume immersed in mercury and the other half in oil. The density of the material of the sphere in g/cm3 is ______.

A nucleus yYx emits one α and two β particles. The resulting nucleus is ______.

Two cars of mass m1 and m2 are moving in circles of radii r1 and r2, respectively. Their speeds are such that they make complete circles at the same time t. The ratio of their centripetal acceleration is:

The valance electrons in alkali metal is a:-

The mass number of a nucleus is equal to the number of:-

Are the nucleons fundamental particles, or do they consist of still smaller parts? One way to find out is to probe a nucleon just as Rutherford probed an atom. What should be the kinetic energy of an electron for it to be able to probe a nucleon? Assume the diameter of a nucleon to be approximately 10–15 m.

A nuclide 1 is said to be the mirror isobar of nuclide 2 if Z1 = N2 and Z2 = N1. (a) What nuclide is a mirror isobar of 1123 Na? (b) Which nuclide out of the two mirror isobars have greater binding energy and why?

Mass numbers of two nuclei are in the ratio of 4 : 3. Their nuclear densities will be in the ratio of ______.

Which of the following are the constituents of the nucleus?

What conclusion is drawn from Rutherford’s scattering experiment of α-particles?


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