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Quick Quiz 1. State the principle of conservation of energy. 2. What energy change takes place when an object falls? 3. A skateboarder slows down when rolling along flat ground. What happens to the kinetic energy of the boarder? 4. The chemical energy in a battery is changed into kinetic by an electric motor. Why is the motor not 100% efficient? 5. Define power? 6. State three types of renewable energy? 7. State a disadvantage of solar power. 8. State an advantage of wind power. 9. Name three fossil fuels. 10. Why is oil non-renewable? 11. What can a transformer do to an a.c. voltage? 12. What type of field exists around a current carrying wire? 13. Name the particles found in the nucleus of an atom. 14. Describe the difference between a.c. and d.c. electricity. 15. What is measured in coulombs? 16. What can accelerate a charged particle? 17. What is potential difference or voltage? 18. What single meter can measure resistance? 19. Do electric field lines travel towards or away from a positive charge? 20. Describe the shape of graph produced by Ohm’s Law. 21. What is constant in Ohm’s Law? 22. In a graph of voltage against current what is the gradient equal to? 23. The resistance of a lamp varies with current. Why does it do this? 24. How does a thermistor’s resistance change as the temperature increases? 25. What is true about the current in a series circuit? 26. In what type of circuit is the voltage constant across all components? 27. When we increase the resistance of a variable resistor a lamp dims. Why does it dim? 28. What advantage is there in connecting appliances in parallel? 29. State an advantage of using a ring circuit. 30. Name three input devices. 31. State the energy change in a loudspeaker. 32. Why is it important to connect an LED the right way round? 33. Why is there usually a series resistor connected to an LED? 34. Name an input device that converts light energy into electrical energy? 35. Which component has a lower resistance when exposed to light? 36. What type of transistor will switch on when +2 V are applied to the gate? 37. What is the switch on voltage of an NPN transistor? 38. What type of transistor has a terminal called a drain? 39. What energy change takes place in a resistor? 40. What common unit is equivalent to one joule per second? 41. What are the units of specific heat capacity? 42. What is likely to contain more heat energy: a burning match or a hot cup of coffee? 43. When an ice cube melts does it give out or take in heat? 44. Which change of state involves specific latent heat of fusion? 45. Why does steam at 100 degrees celcius produce a more serious burn to skin than the same mass of water at 100 degrees celcius? 46. Explain how snow shoes work? 47. Explain how you can lay down on a bed of nails and not be injured? 48. In a bicycle pump what happens to the pressure as the volume decreases? 49. What is absolute zero? 50. Explain why a gas container might explode if thrown into a fire? Answers 1. Energy cannot be created or destroyed, it just changes form. 2. Potential Kinetic 3. The force of friction converts kinetic energy into heat. 4. Resistance in the wires converts electrical into heat. 5. Energy per unit time 6. Wind, waves, solar, geothermal, hydro, biomass, tidal 7. It only works in sunshine. Needs a large area to produce a modest amount of energy. 8. No CO2 is produced. No pollution. Inexpensive 9. Coal, oil and gas 10. It takes millions of years to form. 11. The size of voltage 12. Magnetic 13. Protons and neutrons 14. D.C. only flows in one direction. A.C. flows back and forth. 15. Charge (Q) 16. An electric field 17. The energy per unit charge 18. Ohmmeter 19. Away from positive 20. Straight line through the origin 21. Resistance 22. Resistance 23. As temperature increases resistance also increases. 24. TURD Temperature Up Resistance Down 25. It stays the same at all points. 26 Parallel 27. As resistance increases the current decreases and the lamp dims. 28. They can switch on and off individually. 29. Thinner wire can be used. 30. Microphone, solar cell, switch, variable resistor, thermocouple, thermistor, LDR 31. Electrical sound 32. It only conducts in one direction. 33. To protect it from too much current flowing through it. 34. Solar cell 35. LDR 36. n channel enhancement MOSFET 37. +0.7 V 38. n channel enhancement MOSFET 39. Electrical Heat 40. watts 41. J kg-1 ⁰C-1 42. A mug of hot coffee 43. Takes in heat 44. Melting or freezing. Solid Liquid 45. Steam, it contains latent heat of vaporisation. 46. Large surface area reduces the pressure on the snow. 47. Lots of nails increase the surface area reducing the pressure on the skin. 48. Pressure increases 49. The lowest temperature possible. No heat energy left. -273 ⁰C, 0 K 50. Increasing temperature increases the speed and kinetic energy of the particles. They strike the walls more often and with greater force increasing the pressure.