Questions on Cathode Ray Tube
Multiple-Choice Questions: Cathode Ray Tube
1. What is the primary purpose of a cathode ray tube?
A) To measure temperature
B) To display images or data
C) To store electrical energy
D) To produce sound waves
E) To detect radiation
2. Who is credited with discovering the electron using the CRT?
A) Ernest Rutherford
B) James Chadwick
C) Robert Millikan
D) J.J. Thomson
E) Niels Bohr
3. What is emitted from the cathode in a cathode ray tube?
A) Light waves
B) Protons
C) Neutrons
D) Electrons
E) Alpha particles
4. What is the charge of cathode rays?
A) Positive
B) Negative
C) Neutral
D) Alternating
E) Varies with pressure
5. In the CRT, electrons travel from:
A) Anode to cathode
B) Positive plate to negative plate
C) Cathode to anode
D) Grid to filament
E) Collector to base
6. Which component emits the cathode rays?
A) Anode
B) Grid
C) Cathode
D) Screen
E) Transformer
7. What happens to cathode rays in the presence of an electric field?
A) They are unaffected
B) They stop completely
C) They are attracted to the negative plate
D) They are attracted to the positive plate
E) They move in a circular path
8. What type of particle are cathode rays made of?
A) Protons
B) Photons
C) Neutrons
D) Electrons
E) Atoms
9. Which experiment led to the calculation of the charge-to-mass ratio of the electron?
A) Oil drop experiment
B) Rutherford gold foil experiment
C) J.J. Thomson’s cathode ray experiment
D) Millikan’s photoelectric experiment
E) Bohr’s spectral line experiment
10. What is the role of the phosphorescent screen in a CRT?
A) Absorbs heat
B) Reflects light
C) Emits light when struck by electrons
D) Creates sound
E) Produces radio waves
11. Why did the cathode rays bend toward the positive plate in Thomson's experiment?
A) They are heavy
B) They are made of light
C) They are negatively charged
D) They are positively charged
E) They are magnetic
12. What did J.J. Thomson’s experiment with the CRT help prove?
A) The atom is indivisible
B) Atoms contain small, negatively charged particles
C) Atoms are made of protons only
D) Light behaves like particles
E) Electrons are in fixed orbits
13. The path of cathode rays can be affected by:
A) Sound
B) Heat
C) Magnetic and electric fields
D) Chemical reactions
E) Color filters
14. What gas pressure is used inside a cathode ray tube?
A) Very high
B) Atmospheric
C) Slightly below atmospheric
D) Low pressure
E) Vacuum
15. Which part of the CRT accelerates the cathode rays?
A) Cathode only
B) Anode
C) Phosphorescent screen
D) Glass envelope
E) Deflection plates
16. What is the material of the cathode usually made of?
A) Plastic
B) Copper
C) Glass
D) Metal
E) Ceramic
17. In early CRT experiments, what caused the glow on the screen?
A) Light from cathode
B) Chemical reaction
C) Fluorescence due to electron impact
D) Air pressure
E) Heat emission
18. Which of the following best describes cathode rays?
A) Waves of sound
B) Streams of electrons
C) Charged atoms
D) Bundles of light
E) Magnetic fields
19. What happens if a magnetic field is applied perpendicular to cathode rays?
A) No effect
B) Rays stop moving
C) Rays bend in a curved path
D) Rays become faster
E) Screen turns dark
20. What conclusion did Thomson draw from his cathode ray tube experiments?
A) Atoms are the smallest unit of matter
B) The nucleus is positively charged
C) Electrons are components of all atoms
D) Neutrons do not exist
E) Energy is quantized
Answer Key with Explanations
1. B – CRTs are mainly used to display images or signals (TVs, monitors, oscilloscopes).
2. D – J.J. Thomson discovered the electron using the CRT.
3. D – Electrons are emitted from the cathode in CRTs.
4. B – Cathode rays are negatively charged.
5. C – Electrons move from cathode (negative) to anode (positive).
6. C – The cathode emits electrons.
7. D – Because electrons are negatively charged, they are attracted to the positive plate.
8. D – Cathode rays consist of electrons.
9. C – J.J. Thomson used the CRT to calculate the electron’s charge-to-mass ratio.
10. C – The screen emits light (glows) when hit by electrons.
11. C – The bending showed electrons have negative charge.
12. B – The experiment showed atoms have internal structure, including negative particles.
13. C – Both electric and magnetic fields can deflect cathode rays.
14. D – CRTs operate under low pressure to allow electron flow.
15. B – The anode accelerates electrons toward the screen.
16. D – The cathode is made of metal that emits electrons.
17. C – The glow is caused by fluorescence when electrons hit the screen.
18. B – Cathode rays are streams of electrons.
19. C – A magnetic field bends cathode rays in a curved path.
20. C – Thomson concluded that electrons exist in all atoms.
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Practical Classroom Applications
- Demonstrate how cathode ray experiments led to the discovery of the electron.
- Compare Thomson's findings with Rutherford's and Millikan's experiments.
- Use diagrams and simulations to illustrate the operation of a cathode ray tube.
- Discuss the impact of electron discovery on atomic theory.
- Explore the historical development of scientific models and experimental methods.
- Integrate chemistry and physics concepts through studies of charged particles.
- Encourage inquiry-based learning focused on evidence and scientific reasoning.
- Prepare students for chemistry and physics examinations and standardized science assessments.
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