ICSE Worksheet for chapter-19 Thermionic Emission and Radioactivity class 10

Worksheet For class 10

This page is prepared by the Academic team of Physics Wallah which consists of ICSE Board Worksheet for Class 10 Physics. Students of Class 10 Physics can get a free Worksheet for Class 10 Physics in PDF format prepared as per the newest syllabus and examination pattern in your schools.

Standard 10 students can practice questions and answers which are given here for Physics in Grade 10 that will help them to improve their knowledge of all important chapters and their topics. Students can also download free pdf of Class 10 Physics Notes prepared by teachers and solve important problems provided here with solutions on daily basis to get more scores in school exams and tests.

If any students need to take the online test to check their concepts or undertstanding then they can visit Physics Quiz for Class 10.

Summary

1. Thermionic emission of hot cathode ray tube - Introduction; principle; deflection of charged particles by electric fields and florescence produced by electrons
2. Radioactivity and changes in the nucleus - Introduction; nucleus and its corresponding properties ; radioactivity as spontaneous disintegration α β γ ; harmful effects and safety precautions for radiations

Section 1 - Objective

Q1. The minimum amount of energy required to emit electrons from a metal surface is called the:

1. Ionization energy
2. Dissociation energy
3. Cohesive energy
4. Work function

Q2. The work function of tungsten coated with barium oxide is nearly:

1. 5eV
2. 10eV
3. 1eV
4. 0.01eV

Q3. The electron emitter must have:

1. Low work function and low melting point
2. High work function and high melting point
3. High work function and low melting point
4. Low work function and high melting point

Q4. A TV tube requires an accelerating voltage of the order:

1. 150 volt
2. 1000 volt
3. 20 kV
4. 500 kV

Q5. Electrons was discovered by:

1. Neil Bohr
2. J.J. Thomson
3. R.A. Millikan
4. Rutherford

Q6. The charge on an atom is:

1. Positive
2. Negative
3. Neutral
4. None of these

Q7. Isotone of an element has –

1. Same number of electrons
2. Same number of protons
3. Same number of neutrons
4. Same number of neutrons and protons

Q8. An isotones of ₃₂Ge⁷⁶ is

1. ₃₂ Ge⁷⁷
2. ₃₃Ge⁷⁷
3. ₃₆Ge⁷⁷
4. ₃₄Ge⁷⁷

Q9. The triad of nuclei that is isotonic is:

1. ¹⁴₆C_, ¹⁵₇N , ¹⁷₉F
2. ¹²₆C, ¹⁴₇N ,¹⁹₉F
3. ¹⁴₆C, ¹⁴₇N, ¹⁷₉F
4. ¹⁴₆C, ¹⁴₇N, ¹⁹₉F

Q10. An example of nuclear fusion reaction is:

1. ²³³₉₀Th + ¹₀n → ²³⁴₉₀Th
2. ²⁷₁₃Al + ⁴₂He → ³⁰₁₅P + ¹₀n
3. ³₂He + ³₂He → ⁴₂He + 2¹₁H
4. ²³⁹₉₂U → ²³⁹₉₃Np + ⁰_-1e

Q11. Which particle is used to bombard ₁₃Al²⁸ to give ₁₅P³¹ and a neutron?

1. α-particle
2. Deuteron
3. Proton
4. Neutron

Q12. Gamma rays are:

1. High energy electrons
2. Low energy electrons
3. High energy electromagnetic waves
4. High energy positrons

Q13. Which of the following radiation is least penetrating?

1. α-particles
2. β- particles
3. X-rays
4. γ – radiations

Q14. Which of the following radiation suffers maximum deflection in a magnetic field ?

1. α-particles
2. β-particles
3. X-rays
4. γ – radiations

Section 2 - Subjective

Q1. Define the term work function of a metal

Q2. State any three properties of α ,β and γ rays.

Q3. What do you mean by thermionic emission? State its two properties

Q4. _XRn^Y→ ₈₆Po²¹⁸ + alpha- particles. Find X And Y.

Q5. In the labelled diagram answer the following

• What is represented by symbols A, B, C, D and E?
• States the purpose of A,’B,C and D.

Q6. Give one use of radio – isotopes. What is meant by backgroung radiations?

Q7. Name a common device where a hot cathode ray tube is used.

• State the two properties which a substance should posses when used as thermionic emitter.

Solutions: to worksheet-19 Topic-Thermionic Emission and Radioactivity

1. D	2. C	3. D	4. C	5. B	6. C	7. C
8. B	9. A	10. C	11. A	12. C	13. A	14. B

Subjective Problems

4. X=88, Y = 222

5. (i) A – Indirectly heated cathode

B – Electron beam

C – Anode

D – Plates to apply electric field

E – Filament

(ii) Purpose:

A – indirectly heated cathode emits electrons by passing current in the filament.

B – waves on screen

C – anode imparts a large velocity to the electron beam passing through its hole.

D – electric field is produced by applying between the plates