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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 203 · 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.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  2. 2.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) the widest gap (d) any band
  4. 4.🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
  6. 6.🧩 Which component smooths a wobbly supply? (a) transistor (b) capacitor (c) motor (d) fuse
  7. 7.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V × I (c) R = I ÷ V (d) R = V + I
  8. 8.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  10. 10.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🔺 A 3 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  12. 12.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) current (c) resistance (d) voltage
  14. 14.🌈 A resistor has the colour bands grey, green, black. What is its value (in ohms)?
  15. 15.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) bigger (d) smaller
  16. 16.📏 How many watts (W) is 2.1 kW?
  17. 17.🌈 A resistor has the colour bands grey, red, black. What is its value (in ohms)?
  18. 18.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  19. 19.True or false: energy used each second is measured in ohms (Ω). (a) False (b) True
  20. 20.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 watt (c) 1 volt (d) 1 kilowatt-hour (kWh)
  21. 21.📏 How many amperes (A) is 170 mA? =
  22. 22.True or false: a fuse blows if current is high. (a) True (b) False
  23. 23.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
  24. 24.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
  25. 25.🌈 A resistor has the colour bands yellow, yellow, brown. What is its value (in ohms)?
  26. 26.🧮 A 13 V battery is joined to 3 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  27. 27.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🌈 In the resistor colour code, which number does orange stand for?
  29. 29.🧮 Resistors of 68 Ω, 470 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  30. 30.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  31. 31.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  32. 32.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water tank lid (c) the water pressure (d) the pipe colour
  33. 33.🌈 A resistor has the colour bands orange, grey, red. What is its value (in ohms)?
  34. 34.💡 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)?
  35. 35.🧮 Resistors of 10 Ω, 220 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  36. 36.🔺 A current of 1.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 25 % (d) 0 %
  38. 38.True or false: the flow of charge is measured in volts (V). (a) False (b) True
  39. 39.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  40. 40.🧮 A 3.6 V battery is joined to 6 Ω and 12 Ω resistors in series. What current flows (in amperes)? =

Answer key

  1. 920
  2. 16
  3. the one nearest an end
  4. 6
  5. P = V × I
  6. capacitor
  7. R = V ÷ I
  8. 1.2
  9. anode (+)
  10. 12.5
  11. 0.2
  12. 4.5
  13. resistance
  14. 85
  15. bigger
  16. 2100
  17. 82
  18. 460
  19. False
  20. 1 kilowatt-hour (kWh)
  21. 0.17
  22. True
  23. 315
  24. saves electricity
  25. 440
  26. 1
  27. 3
  28. 3
  29. 868
  30. 1150
  31. 20
  32. the water pressure
  33. 3800
  34. 5
  35. 280
  36. 6
  37. 5 %
  38. False
  39. 300
  40. 0.2

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