Moseley's Law

Q. Which of the following statement is true regarding the hydrogen spectral series?

1. Lyman series is a continuous spectrum and the wavelength range lies in the Ultraviolet region.
2. Paschen series is a line spectrum and the wavelength range lies in the Infrared region.
3. Balmer series is a line spectrum and the wavelength range lies in the Ultraviolet region.
4. The spectral series formula can be derived from the Rutherford model of the atom.

Q. In a photo-emissive cell, with exciting wavelength $\lambda$, the fastest electron has speed $v$. If the exciting wavelength is changed to $\frac{3\lambda }{4},$the speed of the fastest emitted electron will be

1. $v{(4/3)}^{1/2}$
2. $v{(3/4)}^{1/2}$
3. greater than $v{(4/3)}^{1/2}$
4. less than $v{(4/3)}^{1/2}$

Q. X-rays of a particular wavelength are used to irradiate sodium and copper surfaces in two separate experiments and stopping potentials are determined. The stopping potentials are (1) Equal in both cases (2)greater for sodium (3) greater for copper (4) infinitte in both case

Q.

The $K_{\alpha }$ and $K_{\beta }$ X -rays of molybdenum have wavelengths 0.71 $A^{\circ }$ and 0.63 $A^{\circ }$ respectively. Find the wavelength of $L_{\alpha }$ X-ray of molybdenum.

Q.

The frequency of $K_{\alpha }$ line of a source of atomic number Z is proportional to

1. $(Z-1{)}^2$

2. $\frac{1}{Z}$

3. $Z$

4. $Z^2$

Q.

Use Moseley's law with b = 1 to find the frequency of the $K_{\alpha }$ X -ray of La(Z=57) if the frequency of the $K_{\alpha }$ X -ray of Cu(Z-29) is known to be 1.88 $\times {10}^{18}$ Hz.

Q. 22.Deuterium atom in the ground state are radiated by a photon of energy 12.8 eV. What will be the energy of induced radiation of longest wavelength? (Ionisation energy of deuterium is 14.4 eV)

Q. A target element $A$ is bombarded with electrons and the wavelengths of the characteristic spectrum are measured. A second characteristic spectrum is also obtained because of an impurity in the target. The wavelength of the $K_{\alpha }$ lines are $196\text{pm}$ (element $A$) and $169\text{pm}$ (impurity). If the atomic number of impurity is $z=(10x-1)$. Find the value of $x$.
(atomic number of element $A$ is 27).

Q. Figure shows the intensity-wavelength relations of X-rays coming from two different Coolidge tubes. The solid curve represents the relation for the tube A in which the potential difference between the target and the filament is $V_A$ and the atomic number of the target material is $Z_A$. These quantities are $V_B$ and $Z_B$ for the other tube. Then,

1. > <
2. < <
3. > >
4. < >

Q. A small laser emits light at power $5\text{mW}$ and wavelength $633\text{nm}$. The laser beam is focused (narrowed) until its diameter matches the $1266\text{nm}$ diameter of a sphere placed in its path. The sphere is perfectly absorbing and has density $5\times {10}^3{\text{kg/m}}^3$. What is the magnitude of the acceleration that force alone would give the sphere ?

1. $300{\text{m/s}}^2$
2. $3434{\text{m/s}}^2$
3. $3344{\text{m/s}}^2$
4. $3144{\text{m/s}}^2$

Q. The value of Planck's constant is $6.63\times {10}^{-34}Js$. The speed of light $3\times {10}^{17}nm{s}^{-1}$. Which value is closest to the wavelength in nanometer of a quantum of light with frequency of $6\times {10}^{15}{s}^{-1}$?

1. $10$
2. $25$
3. $50$
4. $75$

Q.

The wavelengths of $K_{\alpha }$ and $L_{\alpha }$ X-rays of a material are 21.3 pm and 141 pm respectively. Find the wavelength of $K_{\beta }$ X-ray of the material.

Q. The ratio of the longest to the shortest wavelengths in Balmer series of hydrogen spectra is-

1. $\frac{5}{4}$
2. $\frac{9}{5}$
3. $\frac{17}{6}$
4. $\frac{25}{9}$

Q.

Continuous X -rays are made to strike a tissue paper soaked with polluted water. The incoming X-rays excite the atoms of the sample by knocking out the electrons from the inner shells. Characteristic X-rays are subsequently emitted. The emitted X-rays are analysed and the intensity is plotted against the wavelength figure. Assuming that only $K_{\alpha }$ intensities are detected, list the elements present in the sample from the plot. Use Moseley's equation

Q. In which of the following transitions will the wavelength be minimum?

(a) n = 5 to n = 4
(b) n = 4 to n = 3
(c) n = 3 to n = 2
(d) n = 2 to n = 1

Q. A hydrogen atom emits ultraviolet radiation of wavelength 102.5 nm. What are the quantum numbers of the states involved in the transition?

Q. An X-ray tube is operating at $12\text{kV}$ and $5\text{mA}$. Calculate speed of electrons (Approx.) striking the target $\left(\text{in order of}{10}^7\text{m/s}\right).$

Q. A cobalt target $($atomic no $=27)$ is bombarded with electrons and the wavelength of its characteristic $X-$ray spectrum are measured. A second weak characteristic spectrum is also found, due to presence of an impurity in the target. The wavelengths of the $K_{\alpha }$ lines are $225\text{pm}$ for cobalt and $100\text{pm}$ for impurity. If the atomic number of impurity is $5N$, find the value of $N$.

1. $10$
2. $40$
3. $5$
4. $8$

Q. In a Coolidge tube
A) The intensity of x-rays is controlled by filament current
B) The intensity of x-rays is controlled by the accelerating voltage.
C) As the accelerating voltage is increased ${\lambda }_{min}$ is decreased
D) ${\lambda }_{min}$ is controlled by filament current

1. a, c
2. b, d
3. b, c
4. a, d

Q. Use Moseley’s law with $b=1$, if the frequency of the $K_{\alpha }\text{X-ray}$ of $Cu(Z=29)$ is known to be $1.88\times {10}^{18}\text{Hz}$, then the frequency of the $K_{\alpha }\text{X-ray}$ of $La(Z=57)$ is $7.52\times {10}^{1x}\text{Hz}$. The value of $x$ is -

1. $2$
2. $4$
3. $6$
4. $8$

Q. In the spectrum of hydrogen atom, the ratio of the longest wavelength in Lyman series, to the longest wavelength in the Balmer series is,

1. $\frac{5}{27}$
2. $\frac{25}{36}$
3. $\frac{4}{9}$
4. $\frac{3}{2}$

Q. the ground state energy of hydrogen atom is -13.6 eV.If anelectron makes a tramnstion from an level of -1.51ev to-3.4eV calculate the wavelenght of spectral line emitted and name the seriesof hydrogen spectrum to ehich it belongs

Q.

${}_{80}^{197}$Hg decays to ${}_{79}^{191}$Au through electron capture with a decay constant of 0.257 per day. (a) What other particle or particles are emitted in the decay ? (b) Assume that the electron is captured from the K shell. Use Moseley's law $\sqrt{v}$ = a(Z-b) with a = 4.95 $\times {10}^7{s}^{-\frac{1}{2}}$ and b= 1 to find the wavelength of the $K_{\alpha }$ X-ray emitted following the electron capture.

Q.

The wavelength of K-alpha characteristic x-rays only depends upon:

1. The atomic energy levels

2. Can't comment

3. Accelerating potential in the Coolidge tube

4. Current in the Coolidge tube setup

Q. For Compton effect with visible light the observed Compton shift is

1. Is almost zero because the electrons appear bound
2. Less than zero
3. Very large because the electrons appear free
4. Very small because the electrons appear free

Q. Find the ratio of de brogile wavelength of an alpha particle and a deutron if they are accelerating through the same potential difference

Q.

The frequency of $K_{\alpha }$ line of a source of atomic number Z is proportional to

1. $Z^2$

2. $(Z-1{)}^2$

3. $\frac{1}{Z}$

4. $Z$

Q. Consider a photon of continuous X-ray and a photon of characteristic X-ray of the same wavelength. Which of the following is/are different for the two photons?
(a) Frequency
(b) Energy
(c) Penetrating power
(d) Method of creation

Q. Which of the following is a correct graph of Energy Vs Momentum of the photon?

1. 
2. 
3. 
4. 

Q. Which of the following represents the relative penetrating power of the three types of radioactive emission in decreasing order?

1. $\beta >\gamma >\alpha$
2. $\gamma >\alpha >\beta$
3. $\beta >\alpha >\gamma$
4. $\gamma >\beta >\alpha$