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Question 1 Imagine a world in which c = 50 m/s. How would the everyday events appear to us?

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Question 2 Both Zarak and Samina are 20 years old. Zarak leaves earth in a spacecraft at 0.8 c while Samina remains on earth. Zarak returns from a trip to star at 30 light years from the earth. Which one will be of greater age? Explain.

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Question 3 Which has more energy; a photon of ultraviolet radiation or a photon of yellow light?

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Question 4 Some stars are observed to be reddish and some are blue. Which stars have the higher temperature? Explain.

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Question 5 An electron and proton are accelerated from rest through same potential difference. Which particle has longer wavelength? Explain.

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Question 6 All objects radiate energy. Explain why then are we not able to see objects in dark room?

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Question 7 If photoelectric effect is observed for some metal can you conclude that the effect will be observed for another metal under the same conditions?

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Question 8 Explain why it is not possible for a particle with rest mass to move faster than the speed of light?

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Question 9 Use photon model to explain why ultraviolet is harmful to your skin while visible light is not?

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Question 10 Why annihilation of an electron and a positron creates a pair of photons and not a single photon?

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Question 11 When a particle’s K.E increases, what happens to its de’ Broglie’s wavelength?
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Question 12 Explain why we can experimentally observe the wavelike properties of electron but not of a billiard ball?

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Question 13 Does a light bulb at temperature 2500 K produces as white light as the sun at 6000 K? Explain.

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Question 14 A beam of red light and a beam of blue light have exactly the same energy. Which light contains the greater number of photons?

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Question 15 In a Compton scattering experiment electron is accelerated straight ahead in the direction of the incident X-ray photon. Which way does the scattering photon move?
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Question 16 Why must the rest mass of photon be zero?

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Question 17 What happens to the total radiations from a black body when its absolute temperature is doubled?

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Question 18 Why do not we observe Compton Effect with visible light?

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Question 19 If the following particles all have the same K.E, which has the shortest wavelength. Electron, Alpha particle, neutron and photon.

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Question 20 If an electron and proton has the same de’ Broglie wavelength, which particle has the greater speed?

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Question 21 An incandescent bulb is connected to dimmer switch. When the bulb operates at full power, it appears white. But as it is dimmed it looks more and more red. Explain.

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