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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 548 · 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.💡 Does it save or waste electricity to iron one shirt at a time? (a) saves electricity (b) wastes electricity
  2. 2.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  3. 3.🔺 A 0.4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  4. 4.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  5. 5.🧮 A 1.2 V battery is joined to 2 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  6. 6.⚡ A 7.5 W device works on 5 V. What current does it take (in amperes)? =
  7. 7.💡 An LED is joined to a 9 V battery through a 330 Ω 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
  8. 8.🌈 A resistor has the colour bands red, brown, orange. What is its value (in ohms)?
  9. 9.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  11. 11.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🧮 A 0.6 V battery is joined to 4 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  13. 13.🔺 A current of 20 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 watt (c) 1 kilowatt-hour (kWh) (d) 1 volt
  15. 15.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a motor (c) an LED (d) a fuse
  16. 16.💡 What does LED stand for? (a) large electric dial (b) light-emitting diode (c) light energy dial (d) low energy device
  17. 17.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  18. 18.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 55000 Ω resistor? (a) green-green-yellow (b) green-green-red (c) green-blue-orange (d) green-green-orange
  19. 19.Which of these is measured in watts (W)? (a) how much a part resists (b) current (c) energy used each second (d) the flow of charge
  20. 20.🔺 An 18 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  21. 21.True or false: a fuse blows if current is high. (a) False (b) True
  22. 22.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  23. 23.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  24. 24.📏 How many kilo-ohms (kΩ) is 7700 Ω? =
  25. 25.📏 How many ohms (Ω) is 1.2 kΩ?
  26. 26.What does a transistor do? (a) is a resistance knob (b) blows if current is high (c) beeps for an alarm (d) boosts a small signal
  27. 27.Which of these wastes electricity? (a) unplug idle chargers (b) run fans in empty rooms (c) set the AC to 24 °C (d) use LED lamps
  28. 28.💡 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)?
  29. 29.📏 How many watts (W) is 3 kW?
  30. 30.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  31. 31.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V ÷ I (d) P = V × I
  32. 32.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  33. 33.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  34. 34.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  36. 36.🔺 A current of 0.25 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
  38. 38.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 67000 Ω resistor? (a) blue-violet-red (b) violet-blue-orange (c) blue-violet-orange (d) blue-violet-yellow
  39. 39.🌈 A resistor has the colour bands brown, black, yellow. What is its value in kilo-ohms (kΩ)? =
  40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1900 Ω resistor? (a) white-brown-red (b) brown-white-orange (c) brown-white-red (d) brown-white-brown

Answer key

  1. wastes electricity
  2. voltmeter
  3. 0.1
  4. 345
  5. 0.1
  6. 1.5
  7. lights up
  8. 21000
  9. 1.25
  10. 5
  11. 0.75
  12. 0.1
  13. 6.6
  14. 1 kilowatt-hour (kWh)
  15. a motor
  16. light-emitting diode
  17. cathode (−)
  18. green-green-orange
  19. energy used each second
  20. 1.5
  21. True
  22. 50
  23. anode (+)
  24. 7.7
  25. 1200
  26. boosts a small signal
  27. run fans in empty rooms
  28. 5
  29. 3000
  30. 1840
  31. P = V × I
  32. 15
  33. 10
  34. 8.8
  35. 100
  36. 10
  37. False
  38. blue-violet-orange
  39. 100
  40. brown-white-red

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