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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 968 · 40 questions
TalentJR

Remember (Find the topic, use the formula): Find the topic and the formula: V = I × R, I = V ÷ R, R = V ÷ I, P = V × I, units = W × h ÷ 1000. Change mA to A and kΩ to Ω before using a formula. Check: put your answer back into the formula.

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  1. 1.Which of these is measured in volts (V)? (a) current (b) the flow of charge (c) how much a part resists (d) voltage
  2. 2.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) energy used each second (d) the length of a wire
  3. 3.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) an LED lamp (c) a candle (d) a filament bulb
  4. 4.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
  5. 5.Which of these saves electricity? (a) use old filament bulbs (b) iron one shirt at a time (c) switch off empty rooms (d) run fans in empty rooms
  6. 6.🔺 A current of 2 A flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  8. 8.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  9. 9.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) the gold band (d) any band
  10. 10.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  11. 11.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) their sum (d) less than either one
  12. 12.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 watt (c) 1 volt (d) 1 ampere
  13. 13.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
  14. 14.🔺 A current of 0.1 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) does not light (b) may burn out (c) lights up
  16. 16.💡 An LED is joined to a 12 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) may burn out (c) does not light
  17. 17.⚡ A 72 W device works on 24 V. What current does it take (in amperes)? =
  18. 18.🧮 Resistors of 470 Ω, 47 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  19. 19.🔺 A current of 1.5 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🌈 A resistor has the colour bands violet, black, red. What is its value in kilo-ohms (kΩ)? =
  21. 21.🔺 A current of 0.2 A flows when 0.8 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.🧩 Which component makes things spin? (a) transistor (b) capacitor (c) fuse (d) motor
  23. 23.What does a transistor do? (a) is a resistance knob (b) boosts a small signal (c) senses how bright it is (d) has coloured bands
  24. 24.💡 An LED is joined to a 6 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) does not light (c) may burn out
  25. 25.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  26. 26.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  27. 27.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
  28. 28.True or false: to use old filament bulbs wastes electricity. (a) False (b) True
  29. 29.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = R ÷ I (d) V = I × R
  30. 30.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
  31. 31.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
  32. 32.🔺 A 1.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  33. 33.True or false: energy used each second is measured in watts (W). (a) False (b) True
  34. 34.🔺 A current of 0.1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
  36. 36.True or false: to close the fridge quickly saves electricity. (a) False (b) True
  37. 37.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  38. 38.Which of these saves electricity? (a) iron one shirt at a time (b) run fans in empty rooms (c) set the AC to 24 °C (d) leave fridge door open
  39. 39.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 5 V supply. What current flows (in mA)?
  40. 40.🌈 A resistor has the colour bands blue, green, black. What is its value (in ohms)?

Answer key

  1. voltage
  2. energy used each second
  3. an LED lamp
  4. P = V × I
  5. switch off empty rooms
  6. 10
  7. 0.1
  8. lights up
  9. the one nearest an end
  10. 1840
  11. less than either one
  12. 1 kilowatt-hour (kWh)
  13. 204
  14. 0.5
  15. does not light
  16. may burn out
  17. 3
  18. 527
  19. 8
  20. 7
  21. 4
  22. motor
  23. boosts a small signal
  24. may burn out
  25. anode (+)
  26. 10
  27. 5 %
  28. True
  29. V = I × R
  30. 5
  31. 306
  32. 0.1
  33. True
  34. 0.6
  35. 441
  36. True
  37. 1150
  38. set the AC to 24 °C
  39. 10
  40. 65

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