ENTRANCE TEST – 2011 Multiple Questions and Answers.
Exercise Questions ::
PHYSICS
| 21. | Which of the following is true for Lasers? |
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| A. | Electrons are emitted |
| B. | Stimulated emission of electrons is needed |
| C. | Coherent monochromatic light is emitted |
| D. | There is a population inversion of photons |
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| 22. | What is meant by spontaneous emission of electrons in solids? |
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| A. | Electrons being emitted by the solids through photoelectric effect when irradiated with electromagnetic radiation |
| B. | Incident electrons colliding with electrons in solids and releasing doubling the number of incident electrons |
| C. | Electrons in solids are emitted without any external stimulus through radiation |
| D. | Excited electrons going back to lower energy states immediately by releasing energy. |
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| 23. | When electrons lose all their kinetic energy in the first collision, the entire kinetic appears as an X-ray photon of energy: |
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| A. | K.E = eV |
| B. | K.E = hλmin /c |
| C. | K.E = hc /λmin |
| D. | K.E = h /λmax |
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| 24. | The characteristic X-ray spectrum is due to: |
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| A. | The absorption of neutrons by target material |
| B. | The bombardment of target material by protons |
| C. | The bombardment of target material by electrons |
| D. | The bombardment of target material by alpha particles |
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| 25. | Ionizing capability of gamma rays is: |
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| A. | Equal to alpha and beta particle |
| B. | Less than alpha but greater than beta particles |
| C. | Less than both alpha and beta particles |
| D. | Less than beta but greater than alpha particles |
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