Rutherford's Observations

Q.

When the velocity of a relativistic charged particle increases, its specific charge ______.

Q. When a silver foil (Z = 47) was used in a $\alpha$-ray scattering experiment, the number of $\alpha$ particles scattered at ${30}^{\circ }$ was found to be 200 per minute. If the silver foil is replaced by aluminium (z = 13) foil of same thickness, the number of $\alpha$ -particles scattered per minute at ${30}^{\circ }$ is nearly equal to

1. 15
2. 30
3. 10
4. 20

Q. If number of scattering particles are 56 for ${90}^{\circ }$ angle then the number of scattering particles at ${60}^{\circ }$ angle will be

1. 98
2. 108
3. 224
4. 256

Q. Rutherford stated that the electron revolves in circular orbit around the nucleus. According to classical theory, the path of such electron would be,

1. a spiral
2. a circle
3. a parabola
4. a straight line

Q.

A neutron initially at rest, decays into a proton, an electron and an antineutrino. The ejected electron has a momentum of $1.4\times {10}^{-26}kg-\frac{m}{s}$ and the antinuetrino $6.4\times {10}^{-27}kg-\frac{m}{s}$.Find the recoil speed of the proton (a) if the electron and the antineutrino are ejected along the same direction and (b) if they are ejected along perpendicular directions.Mass of the proton =$1.67\times {10}^{-27}kg$.

Q.

When a glass rod is rubbed with resin, a mass of $27.3\times {10}^{-14}g$ is transferred from glass to resin. Find the amount of charge acquired by the glass rod. What is the nature of the charge? (Charge of electron $=1.6\times {10}^{-19}C$, Mass of electron $=9.1\times {10}^{-31}kg$)

Q. At a distance $L$ from a uniformly long wire, a charged particle is thrown radially outwards with a velocity $u$ in the direction perpendicular to the wire. When the particle reaches a distance $2L$ from the wire, its speed is found to be $u\sqrt{2}$ . The magnitude of the velocity when it is at a distance of $16L$ away from the wire is $pu$, where $p$ is (ignore gravity)

Q.

The Bohr atom, in structure, is not very different from the Rutherford atom - you have an electron going around the nucleus in a circular orbit. So even in the Bohr model, the electron must experience some centripetal acceleration. Why is there no radiation in that case, like in the Rutherford's model?

1. Radiation from an accelerating charge is a result of Maxwell's electromagnetic theory, and it works for large scale systems. Bohr argued that at the atomic scale, the physics itself is different, and Maxwell's laws don't apply at certain orbits.
2. An electron in certain 'stationary orbits' do not have any charge but only mass, and hence don't radiate.
3. In Maxwell's theory of electromagnetism, there is no radiation from an accelerating charge for certain values of angular momentum.
4. In the Bohr atom, although the orbital path is circular, the electron does not undergo circular motion, and hence does not experience any centripetal acceleration.

Q.

Choose the correct alternative from the clues given at the end of the each statement:

(a) The size of the atom in Thomson’s model is .......... the atomic size in Rutherford’s model. (much greater than/no different from/much less than.)

(b) In the ground state of .......... electrons are in stable equilibrium, while in .......... electrons always experience a net force.

(Thomson’s model/ Rutherford’s model.)

(c) A classical atom based on .......... is doomed to collapse.

(Thomson’s model/ Rutherford’s model.)

(d) An atom has a nearly continuous mass distribution in a .......... but has a highly non-uniform mass distribution in ..........

(Thomson’s model/ Rutherford’s model.)

(e) The positively charged part of the atom possesses most of the mass in .......... (Rutherford’s model/both the models.)

Q. Which crystal is used in Davisson and Germer experiment?

1. Aluminium
2. Nickel
3. Cobalt
4. Zinc

Q. The stopping potential for photo-electrons ejected from a surface is $4.5\text{V}$ when $155\text{nm}$ photon is incident on the surface. Calculate the stopping potential when $248\text{nm}$ photon is incident on the surface. $(\text{Use}hc=1240\text{eV nm})$

1. $1.5\text{V}$
2. $2.5\text{V}$
3. $2.0\text{V}$
4. $1.2\text{V}$

Q. A proton and an alpha particle having the same kinetic energy are allowed to pass through a uniform magnetic field perpendicular to the direction of their motion. Compare the radii of the paths of proton and alpha particle.

Q. Which element will deflect more number of $\alpha -$particles at a scattering angle of ${30}^{\circ }$?

$Z_A=90,Z_B=85,Z_C=95$ and $Z_D=80$

1. $A$
2. $B$
3. $C$
4. $D$

Q. In scattering experiment, find the distance of closest approach, if a $6MeV\alpha -particle$ is used.

1. $3.2\times {10}^{-16}m$
2. $2\times {10}^{-14}m$
3. $4.6\times {10}^{-15}m$
4. $3.2\times {10}^{-15}m$

Q. a) The size of the atom in the Thomsons model is ........... the atomic size in Rutherford's model.

Q.

Deuteron and alpha particles having the same KE enter in a magnetic field. If the ratio of the radius of Deuteron and alpha particle is $x\sqrt{2}$ . Then $x=$

1. $5$

2. $8$

3. $3$

4. $1$

Q. Match the following:
Table-1 Table-2

$\left(\text{A}\right)L$	$\left(\text{P}\right)\left[M^0{L}^0{T}^{-2}{A}^0\right]$
$\left(\text{B}\right)$ Magnetic flux	$\left(\text{Q}\right)\left[M{L}^2{T}^{-2}{A}^{-1}\right]$
$\left(\text{C}\right)LC$	$\left(\text{R}\right)\left[M{L}^2{T}^{-2}{A}^{-2}\right]$
$\left(\text{D}\right)C{R}^2$	$\left(\text{S}\right)$ None

1. $\text{A}\to \text{R};\text{B}\to \text{Q};\text{C}\to \text{S};\text{D}\to \text{R}$
2. $\text{A}\to \text{Q};\text{B}\to \text{Q};\text{C}\to \text{S};\text{D}\to \text{R}$
3. $\text{A}\to \text{R};\text{B}\to \text{P};\text{C}\to \text{S};\text{D}\to \text{R}$
4. $\text{A}\to \text{P};\text{B}\to \text{Q};\text{C}\to \text{S};\text{D}\to \text{S}$

Q. Which of the following assumption is correct for a recoil of an atom after photon ejection?

1. The mass of an atom is very small compared to mass of the ejected photon.
2. The mass of an atom is very large compared to mass of the ejected photon.
3. The electron is considered to be in second excited state.
4. After the ejection, photon and atom move in same direction.

Q. $\alpha$ particles used in Rutherfords experiments are heavy particles.

1. positively charged
2. negatively charged
3. neutral

Q. Which element will deflect more number of $\alpha -$particles at a scattering angle of ${25}^{\circ }$?

$Z_P=75,Z_Q=80,Z_R=85$ and $Z_S=79$

1. $P$
2. $Q$
3. $R$
4. $S$

Q. If number of scattering particles are 56 for ${90}^{\circ }$ angle then the number of scattering particles at ${60}^{\circ }$ angle will be

1. 224
2. 256
3. 98
4. 108

Q. When a silver foil (Z = 47) was used in a $\alpha$-ray scattering experiment, the number of $\alpha$ particles scattered at ${30}^{\circ }$ was found to be 200 per minute. If the silver foil is replaced by aluminium (z = 13) foil of same thickness, the number of $\alpha$ -particles scattered per minute at ${30}^{\circ }$ is nearly equal to

1. 15
2. 30
3. 10
4. 20

Q. A proton and an $\alpha$ particle having equal kinetic energy are projected in a uniform transverse electric field as shown in figure

1. Proton trajectory is more curved
2. $\alpha$ particle trajectory is more curve
3. Both trajectories are equally curved but in opposite direction
4. Both trajectories are equally curved and in same direction

Q. Which of the following nuclei shown in the graph is light and stable?

1. $A$
2. $B$
3. $C$
4. $D$

Q. Which of the following nuclei shown in the graph is light and stable?

1. $D$
2. $A$
3. $C$
4. $B$

Q. A radioactive nucleus of mass number $A$, initially at rest, emits an $\alpha$-particle with a speed $v$. The recoil speed of the daughter nucleus will be

1. $\frac{2v}{A+4}$
2. $\frac{2v}{A-4}$
3. $\frac{4v}{A-4}$
4. $\frac{4v}{A+4}$

Q. A hydrogen atom moving at a speed $v$ absorbs a photon of wavelength $122\text{nm}$ and stops. The value of $v$ is (mass of hydrogen atom $=1.67\times {10}^{-27}\text{kg}$)

1. $3.25\text{m/sec}$
2. $6.25\text{m/sec}$
3. $9.25\text{m/sec}$
4. $12.25\text{m/sec}$

Q. The masses of $\alpha$ -particle, proton and neutron are $4.00150$ amu, $1.00728$ amu and $1.00867$ amu respectively. Binding Energy per nucleon of $\alpha$ -particle is :

1. $283J$
2. $28.3MeV$
3. $7.08MeV$
4. $931.5MeV$

Q. In the Davisson and Germer experiment, the velocity of electrons emitted from the electron gun can be increased by

1. increasing the potential difference between the anode and filament
2. increasing the filament current
3. decreasing the filament current
4. decreasing the potential difference between the anode and filament

Q.

How does a Physicist work?