Physics homework XII-25th Feb Sunday

1. What is doppler effect? Find an expression for the change in apparent frequency when the source passes by the stationary observer.
2. Whistle of an approaching train is shriller. Why?
3. A tunning fork has two prongs. Why?
4. In which medium is the angle of polarization greater, rarer or denser?
5. Define a.c.power. Derive an expression for it. Also define power factor.
6. What is wattless current?
7. What do you mean by radiation hazard? What are its safety measures?
8. Give a brief account on "Energy sources of Nepal".
9. Explain the term artificial radio isotopes.
10. What do you mean by dark energy and dark matter?

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Physics homework XII-18thFeb 2018-Sunday

1. What is Doppler's effect? Obtain an expression for the change in apparent frequency when an observer passes by a stationary source.
2. State the laws of radioactivity and derive decay equation.
3. What is green house effect?Discuss its effects, sources and the controlling measures.
4. Discuss the phase relationship between the voltage and current in a.c. circuit containing capacitor and resistor in series and hence derive an expression for the impedance of the circuit.
5. Why is a choke coil better than a resistor in an electrical appliances?
6. What is meant by impedance of an a.c. circuit?
7. What do you mean by curie?
8. What is acid rain? Explain.
9. What is global warming? Explain.
10. What are ultrasonic and infrasonic?
11. Which has a more direct influence on the loudness of a sound wave: the displacement amplitude or the pressure amplitude? Explain.
12. Bats catch their prey in the dark even when they don't see the prey. How can this happen?
13. A tuning fork has two prongs. why?
14. State Hubble's law and write the significance of Hubble's constant.
15. What are quarks? Write their names with charge they contained.

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Physics homework XII-11th February Sunday

1. What are beats? Derive an expression for beat frequency.
2. How is it that one can recognize a friend from his voice without seeing him?
3. What is polarization of light? State and prove Brewster's law.
4. Is polarization possible for longitudinal wave?
5. What is meant by wattless current?
6. What are advantages of a.c over d.c.?
7. Derive the condition for resonant frequency of LCR alternating current circuit.
8. What is noise pollution? Mention its sources and preventions.

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Physics homework grade XII-for 4th Feb Sunday

1. What is pressure amplitude? Obtain an expression for it.
2. Define Intensity of sound. Obtain an expression for it.
3. If the pressure amplitude of a sound wave is halved, by what factor does the intensity of the wave change?
4. What is meant by threshold of hearing?
5. Why is the roaring of lion different than the sound of a mosquito?
6. How is it that one can recognize a friend from his voice without seeing him?
7. A nucleus contains no electrons, yet it ejects them. Explain.
8. How do the mass number and atomic number of a radioactive element change in an alpha, beta and gamma decay?
9. How do beta particles differ from electrons?
10. Discuss the importance of physics for the development of nation.
11. A transformer gets heated up while in use. Why?
12. Find the impedance of LCR circuit in series.

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