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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 347 · 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.

NameDateTime takenScore ___ / 40
  1. 1.🔺 A current of 40 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.📏 How many kilo-ohms (kΩ) is 2700 Ω? =
  3. 3.What does a fuse do? (a) stores a little charge (b) is a resistance knob (c) boosts a small signal (d) blows if current is high
  4. 4.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
  5. 5.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  7. 7.🧮 A 1.6 V battery is joined to 6 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  8. 8.True or false: power is measured in watts (W). (a) True (b) False
  9. 9.🧮 Resistors of 220 Ω, 470 Ω, 47 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  10. 10.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
  12. 12.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  13. 13.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the pipe colour (c) a narrow pipe (d) the flow of water
  14. 14.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.True or false: a thermistor limits the current. (a) False (b) True
  16. 16.⚡ A device works on 5 V and takes 0.5 A. What is its power (in watts)? =
  17. 17.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.True or false: a buzzer senses how hot it is. (a) False (b) True
  20. 20.🔺 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
  21. 21.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a bigger tank (c) a narrow pipe (d) the water pressure
  22. 22.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  24. 24.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
  25. 25.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  26. 26.🌈 A resistor has the colour bands blue, brown, red. What is its value in kilo-ohms (kΩ)? =
  27. 27.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) any band (d) the one nearest an end
  28. 28.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  29. 29.🧩 Which component has coloured bands? (a) resistor (b) LDR (c) fuse (d) potentiometer
  30. 30.🧩 Which component is a resistance knob? (a) potentiometer (b) resistor (c) capacitor (d) motor
  31. 31.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =
  32. 32.🧮 A 1.2 V battery is joined to 2 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  33. 33.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = V ÷ I (d) P = I ÷ V
  34. 34.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
  35. 35.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to make it brighter (d) to limit the current
  36. 36.🌈 A resistor has the colour bands brown, brown, red. What is its value (in ohms)?
  37. 37.🔺 A current of 50 mA flows when 11 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.🧮 A 2.8 V battery is joined to 4 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  39. 39.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an LED lamp (d) an oil lamp
  40. 40.Which of these wastes electricity? (a) switch off empty rooms (b) set the AC to 24 °C (c) use daylight to read (d) leave the TV on standby

Answer key

  1. 200
  2. 2.7
  3. blows if current is high
  4. 0.1
  5. 12
  6. voltmeter
  7. 0.2
  8. True
  9. 747
  10. 1.5
  11. store charge briefly
  12. anode (+)
  13. the flow of water
  14. 2.4
  15. False
  16. 2.5
  17. 0.6
  18. 6
  19. False
  20. I = V ÷ R
  21. a narrow pipe
  22. 2.5
  23. cathode (−)
  24. 4.5
  25. ammeter
  26. 6.1
  27. the one nearest an end
  28. 115
  29. resistor
  30. potentiometer
  31. 3
  32. 0.2
  33. P = V × I
  34. False
  35. to limit the current
  36. 1100
  37. 220
  38. 0.2
  39. an LED lamp
  40. leave the TV on standby

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