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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 666 · 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.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) the water pressure (c) a narrow pipe (d) a bigger tank
  2. 2.🧾 A 100 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  3. 3.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 25 % (d) 0 %
  4. 4.True or false: to use old filament bulbs saves electricity. (a) True (b) False
  5. 5.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  6. 6.🔺 A current of 40 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.What does a motor do? (a) makes a beeping sound (b) turns a fan or wheels (c) limits the current (d) stores a little charge
  8. 8.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  9. 9.What does a potentiometer do? (a) has coloured bands (b) smooths a wobbly supply (c) turns a fan or wheels (d) is a resistance knob
  10. 10.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.True or false: the push of a cell is measured in volts (V). (a) True (b) False
  12. 12.📏 How many amperes (A) is 1540 mA? =
  13. 13.📏 Which unit measures the flow of charge? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
  14. 14.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
  15. 15.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 63000 Ω resistor? (a) blue-orange-red (b) blue-orange-yellow (c) orange-blue-orange (d) blue-orange-orange
  16. 16.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  17. 17.⚡ A 3 W device works on 6 V. What current does it take (in amperes)? =
  18. 18.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a resistor (d) a motor
  19. 19.🔺 A 12 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  20. 20.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
  22. 22.🧮 A 33 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  23. 23.📏 How many kilo-ohms (kΩ) is 900 Ω? =
  24. 24.Which of these wastes electricity? (a) unplug idle chargers (b) use daylight to read (c) run fans in empty rooms (d) switch off empty rooms
  25. 25.⚡ A device works on 9 V and takes 0.2 A. What is its power (in watts)? =
  26. 26.🔺 A current of 40 mA flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  28. 28.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = I ÷ V (c) R = V × I (d) R = V + I
  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.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  31. 31.🧮 A 4 V battery is joined to 10 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  32. 32.🔺 A current of 0.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.🧾 A 100 W appliance runs for 5 hours. How many units (kWh) of electricity does it use? =
  34. 34.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
  35. 35.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 volt (c) 1 watt (d) 1 kilowatt-hour (kWh)
  36. 36.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = R ÷ V (d) I = V + R
  37. 37.🧮 Resistors of 150 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  38. 38.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) their sum (d) less than either one
  39. 39.🔺 A current of 1.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

Answer key

  1. a narrow pipe
  2. 0.2
  3. 5 %
  4. False
  5. 10
  6. 13.2
  7. turns a fan or wheels
  8. 0.1
  9. is a resistance knob
  10. 0.3
  11. True
  12. 1.54
  13. ampere (A)
  14. wastes electricity
  15. blue-orange-orange
  16. anode (+)
  17. 0.5
  18. a motor
  19. 3
  20. 4
  21. energy used each second
  22. 133
  23. 0.9
  24. run fans in empty rooms
  25. 1.8
  26. 300
  27. 460
  28. R = V ÷ I
  29. V = I × R
  30. True
  31. 0.2
  32. 4
  33. 0.5
  34. saves electricity
  35. 1 kilowatt-hour (kWh)
  36. I = V ÷ R
  37. 197
  38. less than either one
  39. 4
  40. 5

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