Class 12 Physics — Chapter 3: Dual Nature of Radiation and Matter

What you'll learn

• ▸Discovery and Properties of the Electron
• ▸Electron Emission and Work Function
• ▸Types of Electron Emission
• ▸The Photoelectric Effect
• ▸Threshold Frequency
• ▸Experimental Setup for Photoelectric Effect

Chapter Summary

--- PAGE 1 --- Chapter Eleven DUAL NATURE OF RADIATION AND MATTER 11.1 INTRODUCTION The Maxwell's equations of electromagnetism and Hertz experiments on the generation and detection of electromagnetic waves in 1887 strongly established the wave nature of light. Towards the same period at the end of 19th century, experimental investigations on conduction of electricity (electric discharge) through gases at low pressure in a discharge tube led to many historic discoveries. The discovery of X-rays by Roentgen in 1895, and of electron by J. J. Thomson in 1897, were important milestones in the understanding of atomic structure. It was found that at sufficiently low pressure of about 0.001 mm of mercury column, a discharge took place between the two electrodes on applying the electric field to the gas in the discharge tube. A fluorescent glow appeared on the glass opposite to cathode. The colour of glow of the glass depended on the type of glass, it being yellowish-green for soda glass. T…

Practice Questions from this Chapter

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1. Explain electron's charge. Get Solution →
2. Describe light as particles. Get Solution →
3. Illustrate the photoelectric effect. Get Solution →
4. Who is credited with the discovery of the electron in 1897? Get Solution →
5. What is the minimum energy required for an electron to escape from a metal surface called? Get Solution →
6. The phenomenon of photoelectric emission was discovered in 1887 by whom? Get Solution →
7. What are electrons emitted from a metal surface due to the illumination of light called? Get Solution →
8. R. A. Millikan's oil-drop experiment was performed for the precise measurement of what quantity? Get Solution →

Did you know?

• 💡 Electrons are so small, a single proton is almost 2000 times heavier than an electron.
• 💡 Every lightning bolt you see is caused by trillions of electrons jumping from clouds to the ground.
• 💡 Light from the Sun takes over eight minutes to travel the 150 million kilometers to Earth.
• 💡 Invisible ultraviolet light from the sun can knock electrons right off certain metal surfaces.
• 💡 Scientists can slow down light to walking speed using special materials and extreme cold.

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