CBSE Physics Electrons and Photons Expected Questions : Unit X
Very Short Answer Type Question
Q. 1. What are cathode rays 7
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Q. 2. Are cathode rays a part of electromagnetic rays ?
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Q. 3. What is the charge and mass of an electron ?
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Q. 4. Does electric discharge through gases take place at atmospheric pressure ?
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Q. 5. In a Thomson’s set-up for determining e/m, the same high tension de supply provides potential to the anode of the accelerating column, as also to the positive deflecting plate in the region of crossed fields, If the supply voltage is doubled, by what factor should the magnetic field be increased to kept the electron beam undeflected ?
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Q. 6. Why should the oil drop of Millikan’s experiment be of microscopic sizes ? Why cannot we experiment with much bigger drops ?
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Q. 7. Why is wave nature of matter not apparent to our daily observations 7
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Q. 8. Stoke’s formula for viscous drag is not really valid for oil drops of extremely minute sizes. Why not ?
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Q. 9. Can photoelectric effect be produced on copper or silver 7
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Q. 10. It is harder to remove electron from copper. Which has higher value of work function ?
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Q. 11. What is the momentum of electrons if their wavelength is 2 A ?
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Q. 12. A proton and an electron have some de—Broglie_wavelength, (i) Which of them moves fast and (ii) which possesses more kinetic energy ? Justify your answer.
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