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H.C. Verma solutions for Class 12 Physics chapter 22 - X-rays

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H.C. Verma Concepts of Physics - Vol. 2

Concepts of Physics - Vol. 2 - Shaalaa.com

Chapter 22: X-rays

Short AnswersMCQOthers

Chapter 22: X-rays Exercise Short Answers solutions [Page 393]

Short Answers | Q 1 | Page 393

When a Coolidge tube is operated for some time it becomes hot. Where does the heat come from?

Short Answers | Q 2 | Page 393

In a Coolidge tube, electrons strike the target and stop inside it. Does the target get more and more negatively charged as time passes?

Short Answers | Q 3 | Page 393

Can X-rays be used for photoelectric effect?

Short Answers | Q 4 | Page 393

Can X-rays be polarised?

Short Answers | Q 5 | Page 393

X-ray and visible light travel at the same speed in vacuum. Do they travel at the same speed in glass?

Short Answers | Q 6 | Page 393

Characteristic X-rays may be used to identify the element from which they are being emitted. Can continuous X-rays be used for this purpose?

Short Answers | Q 7 | Page 393

Is it possible that in a Coolidge tube characteristic Lα X-rays are emitted but not Kα X-rays?

Short Answers | Q 8 | Page 393

Can Lα X-ray of one material have shorter wavelength than Kα X-ray of another?

Short Answers | Q 9 | Page 393

Can a hydrogen atom emit characteristic X-rays?

Short Answers | Q 10 | Page 393

Why is exposure to X-rays injurious to health but not exposure to visible light, when both are electromagnetic waves?

Chapter 22: X-rays Exercise MCQ solutions [Pages 393 - 394]

MCQ | Q 1 | Page 393

An X-ray beam can be deflected

  • by an electric field

  • by a magnetic field

  • by an electric field as well as a magnetic field

  • neither by an electric field nor a magnetic field

MCQ | Q 2 | Page 393

Consider a photon of a continuous X-ray coming from a Coolidge tube. Its energy comes from

  • the kinetic energy of the striking electron

  • the kinetic energy of the free electrons of the target

  • the kinetic energy of the ions of the target

  • an atomic transition in the target

MCQ | Q 3 | Page 393

The energy of a photon of a characteristic X-ray from a Coolidge tube comes from

  •  the kinetic energy of the striking electron

  •  the kinetic energy of the free electrons of the target

  • the kinetic energy of the ions of the target

  • an atomic transition in the target

MCQ | Q 4 | Page 393

If the potential difference applied to the tube is doubled and the separation between the filament and the target is also doubled, the cutoff wavelength

  • will remain unchanged

  • will be doubled

  • will be halved

  • will become four times the original

MCQ | Q 5 | Page 394

If the current in the circuit for heating the filament is increased, the cutoff wavelength

  • will increase

  • will decrease

  • will remain unchanged

  • will change

MCQ | Q 6 | Page 394

Moseley's Law for characteristic X-ray is √v = a(Z − b). Here,

  • both a and b are independent of the material

  • a is independent but b depends on the material

  • b is independent but a depends on the material

  • both a and b depend on the material

MCQ | Q 7 | Page 394

Frequencies of Kα X-rays of different materials are measured. Which one of the graphs in the figure may represent the relation between the frequency v and the atomic number ?

MCQ | Q 8 | Page 394

The X-ray beam emerging from an X-ray tube

  • is monochromatic

  • has all wavelengths smaller than a certain maximum wavelength

  • has all wavelengths greater than a certain minimum wavelength

  • has all wavelengths lying between a minimum and a maximum wavelength

MCQ | Q 9 | Page 394

One of the following wavelengths is absent and the rest are present in the X-rays coming from a Coolidge tube. Which one is the absent wavelength?

  • 25 pm

  • 50 pm

  • 75 pm

  • 100 pm

MCQ | Q 10 | Page 394

The 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 VA and the atomic number of the target material is ZA. These quantities are VB and ZB for the other tube. Then,

  • VA > VB, ZA > ZB

  • VA > VB, ZA < ZB

  • VA < VB, ZA > ZB

  • VA > VB, ZA < ZB

MCQ | Q 11 | Page 394

50% of the X-rays coming from a Coolidge tube are able to pass through a 0.1 mm thick aluminium foil. If the potential difference between the target and the filament is increased, the fraction of the X-rays passing through the same foil will be

  • 0%

  • < 50%

  • 50 %

  • > 50%

MCQ | Q 12 | Page 394

50% of the X-ray coming from a Coolidge tube is able to pass through a 0.1 mm thick aluminium foil. The potential difference between the target and the filament is increased. The thickness of the aluminium foil that will allow 50% of the X-ray to pass through will be

  • zero

  • < 0.1 mm

  • 0.1 mm

  • > 0.1 mm

MCQ | Q 13 | Page 394

X-ray from a Coolidge tube is incident on a thin aluminium foil. The intensity of the X-ray transmitted by the foil is found to be I0. The heating current is increased to increase the temperature of the filament. The intensity of the X-ray transmitted by the foil will be
(a) zero
(b) < I0
(c) I0
(d) > I0

  • zero

  • < I0

  • I0

  • > I0

MCQ | Q 14 | Page 394

Visible light passing through a circular hole forms a diffraction disc of radius 0.1 mm on a screen. If an X-ray is passed through the same setup, the radius of the diffraction disc will be

  • zero

  • < 0.1 mm

  • 0.1 mm

  • > 0.1 m

Chapter 22: X-rays Exercise MCQ solutions [Pages 365 - 395]

MCQ | Q 1 | Page 394

For harder X-rays,
(a) the wavelength is higher
(b) the intensity is higher
(c) the frequency is higher
(d) the photon energy is higher.

MCQ | Q 2 | Page 394

Cutoff wavelength of X-rays coming from a Coolidge tube depends on the
(a) target material
(b) accelerating voltage
(c) separation between the target and the filament
(d) temperature of the filament.

  • target material

  • accelerating voltage

  • separation between the target and the filament

  • temperature of the filament.

MCQ | Q 3 | Page 394

Mark the correct options.
(a) An atom with a vacancy has smaller energy that a neutral atom.
(b) K X-ray is emitted when a hole makes a jump from the K shell to some other shell.
(c) The wavelength of K X-ray is smaller than the wavelength of L X-ray of the same material.
(d) The wavelength of Kα X-ray is smaller than the wavelength of Kβ X-ray of the same material.

MCQ | Q 4 | Page 394

For a given material, the energy and wavelength of characteristic X-rays satisfy
(a) E(Kα) > E(Kβ) > E(Kγ)
(b) E(Mα) > E(Lα) > E(Kα)
(c) λ(Kα) > λ(Kβ) > λ(Kγ)
(d) λ(Mα) > λ(Lα) > λ(Kα).

MCQ | Q 5 | Page 394

The potential difference applied to an X-ray tube is increased. As a result, in the emitted radiation,
(a) the intensity increases
(b) the minimum wavelength increases
(c) the intensity remains unchanged
(d) the minimum wavelength decreases.

MCQ | Q 6 | Page 394

When an electron strikes the target in a Coolidge tube, its entire kinetic energy
(a) is converted into a photon
(b) may be converted into a photon
(c) is converted into heat
(d) may be converted into heat.

MCQ | Q 7 | Page 365

X-ray incident on a material
(a) exerts a force on it
(b) transfers energy to it
(c) transfers momentum to it
(d) transfers impulse to it.

MCQ | Q 8 | Page 395

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?

  • Frequency

  • Energy

  • Penetrating power

  • Method of creation

Chapter 22: X-rays solutions [Pages 395 - 396]

Q 1 | Page 395

Find the energy, the frequency and the momentum of an X-ray photon of wavelength 0.10 nm.

(Use Planck constant h = 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 2 | Page 395

Iron emits Kα X-ray of energy 6.4 keV. Calculate the times taken by an iron Kα photon to cross through a distance of 3 km.

(Use Planck constant h = 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 3 | Page 395

Find the cutoff wavelength for the continuous X-rays coming from an X-ray tube operating at 30 kV.

(Use Planck constant h = 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 4 | Page 395

What potential difference should be applied across an X-ray tube to get X-ray of wavelength not less than 0.10 nm? What is the maximum energy of a photon of this X-ray in joule?

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 5 | Page 395

The X-ray coming from a Coolidge tube has a cutoff wavelength of 80 pm. Find the kinetic energy of the electrons hitting the target.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 6 | Page 395

If the operating potential in an X-ray tube is increased by 1%, by what percentage does the cutoff wavelength decrease?

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 7 | Page 395

The distance between the cathode (filament) and the target in an X-ray tube is 1.5 m. If the cutoff wavelength is 30 pm, find the electric field between the cathode and the target.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 8 | Page 395

The short-wavelength limit shifts by 26 pm when the operating voltage in an X-ray tube is increased to 1.5 times the original value. What was the original value of the operating voltage?

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 9 | Page 395

The electron beam in a colour TV is accelerated through 32 kV and then strikes the screen. What is the wavelength of the most energetic X-ray photon?

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 10 | Page 395

When 40 kV is applied across an X-ray tube, X-ray is obtained with a maximum frequency of 9.7 × 1018 Hz. Calculate the value of Planck constant from these data.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 11 | Page 395

An X-ray tube operates at 40 kV. Suppose the electron converts 70% of its energy into a photon at each collision. Find the lowest there wavelengths emitted from the tube. Neglect the energy imparted to the atom with which the electron collides.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 12 | Page 395

The wavelength of Kα X-ray of tungsten is 21.3 pm. It takes 11.3 keV to knock out an electron from the L shell of a tungsten atom. What should be the minimum accelerating voltage across an X-ray tube having tungsten target which allows production of Kα X-ray?

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 13 | Page 395

The Kβ X-ray of argon has a wavelength of 0.36 nm. The minimum energy needed to ionize an argon atom is 16 eV. Find the energy needed to knock out an electron from the K shell of an argon atom.

Q 14 | Page 395

The Kα X-rays of aluminium (Z = 13) and zinc (Z = 30) have wavelengths 887 pm and 146 pm respectively. Use Moseley's  law √v = a(− b) to find the wavelengths of the Kα X-ray of iron (Z = 26).

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 15 | Page 395

A certain element emits Kα X-ray of energy 3.69 keV. Use the data from the previous problem to identify the element.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 16 | Page 395

The Kβ X-rays from certain elements are given below. Draw a Moseley-type plot of √v versus Z for Kβ radiation.

Element Ne P Ca Mn Zn Br
Energy (keV) 0.858 2.14 4.02 6.51 9.57 13.3
Q 17 | Page 395

The Kα and Kβ X-rays of molybdenum have wavelengths 0.71 A and 0.63 A respectively. Find the wavelength of Lα X-ray of molybdenum.

Q 18 | Page 395

The Kα and Kβ X-rays of molybdenum have wavelengths 0.71 A and 0.63 A respectively. Find the wavelength of Lα X-ray of molybdenum.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 19 | Page 395

The wavelengths of Kα and Lα X-rays of a material are 21.3 pm and 141 pm respectively. Find the wavelength of Kβ X-ray of the material.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 20 | Page 395

The energy of a silver atom with a vacancy in K shell is 25.31 keV, in L shell is 3.56 keV and in M shell is 0.530 keV higher than the energy of the atom with no vacancy. Find the frequency of Kα, Kβ and Lα X-rays of silver.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 21 | Page 395

Find the maximum potential difference which may be applied across an X-ray tube with tungsten target without emitting any characteristic K or L X-ray. The energy levels of the tungsten atom with an electron knocked out are as follows.

Cell containing vacancy K L M
Energy in keV 69.5 11.3 2.3
Q 22 | Page 395

The electric current in an X-ray tube (from the target to the filament) operating at 40 kV is 10 mA. Assume that on an average, 1% of the total kinetic energy of the electron hitting hte target are converted into X-rays.
(a) What is the total power emitted as X-rays and (b) how much heat is produced in the target every second?

Q 23 | Page 395

Heat at the rate of 200 W is produced in an X-ray tube operating at 20 kV. Find the current in the circuit. Assume that only a small fraction of the kinetic energy of electrons is converted into X-rays.

Q 24 | Page 396

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 analysed and the intensity is plotted against the wavelength. Assuming that only Kα intensities are detected, list the elements present in the sample from the plot. Use Moseley's equation v − (25 × 1014Hz)(Z − 1)2.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 25 | Page 396

A free atom of iron emits Kα X-rays of energy 6.4 keV. Calculate the recoil kinetic energy of the atom. Mass of an iron atom = 9.3 × 10−26 kg.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 26 | Page 396

The stopping potential in a photoelectric experiment is linearly related to the inverse of the wavelength (1/λ) of the light falling on the cathode. The potential difference applied across an X-ray tube is linearly related to the inverse of the cutoff wavelength (1/λ) of the X-ray emitted. Show that the slopes of the lines in the two cases are equal and find its value.

(Use Planck constant h = 6.63 × 10-34 Js= 4.14 × 10-15 eVs, speed of light c = 3 × 108 m/s.)

Q 27 | Page 396

Suppose a monochromatic X-ray beam of wavelength 100 pm is sent through a Young's double slit and the interference pattern is observed on a photographic plate placed 40 cm away from the slit. What should be the separation between the slits so that the successive maxima on the screen are separated by a distance of 0.1 mm?

Chapter 22: X-rays

Short AnswersMCQOthers

H.C. Verma Concepts of Physics - Vol. 2

Concepts of Physics - Vol. 2 - Shaalaa.com

H.C. Verma solutions for Class 12 Physics chapter 22 - X-rays

H.C. Verma solutions for Class 12 Physics chapter 22 (X-rays) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the CBSE Concepts of Physics - Vol. 2 solutions in a manner that help students grasp basic concepts better and faster.

Further, we at Shaalaa.com provide such solutions so that students can prepare for written exams. H.C. Verma textbook solutions can be a core help for self-study and acts as a perfect self-help guidance for students.

Concepts covered in Class 12 Physics chapter 22 X-rays are Elementary Facts About Electromagnetic Wave Uses, Electromagnetic Spectrum, Transverse Nature of Electromagnetic Waves, Electromagnetic Waves, Displacement Current, Einstein’S Photoelectric Equation: Energy Quantum of Radiation, Particle Nature of Light: the Photon, Photoelectric Effect and Wave Theory of Light, Experimental Study of Photoelectric Effect, Einstein’s Equation - Particle Nature of Light, Electron Emission, Davisson-Germer Experiment, de-Broglie Relation, Wave Nature of Matter, Photoelectric Effect - Hallwachs’ and Lenard’S Observations, Photoelectric Effect - Hertz’S Observations, Dual Nature of Radiation.

Using H.C. Verma Class 12 solutions X-rays exercise by students are an easy way to prepare for the exams, as they involve solutions arranged chapter-wise also page wise. The questions involved in H.C. Verma Solutions are important questions that can be asked in the final exam. Maximum students of CBSE Class 12 prefer H.C. Verma Textbook Solutions to score more in exam.

Get the free view of chapter 22 X-rays Class 12 extra questions for Physics and can use Shaalaa.com to keep it handy for your exam preparation

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