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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 873 · 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 current of 0.25 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.Which of these saves electricity? (a) run fans in empty rooms (b) leave fridge door open (c) use old filament bulbs (d) set the AC to 24 °C
  4. 4.🧮 A 220 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)?
  5. 5.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  6. 6.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.⚡ A 1.5 W device works on 6 V. What current does it take (in amperes)? =
  8. 8.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
  9. 9.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
  10. 10.📏 How many milliamperes (mA) is 0.88 A?
  11. 11.⚡ A 0.375 W device works on 1.5 V. What current does it take (in amperes)? =
  12. 12.🌈 In the resistor colour code, which number does black stand for?
  13. 13.🔺 A current of 0.2 A flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  16. 16.🔺 A current of 50 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.True or false: the flow of charge is measured in ohms (Ω). (a) True (b) False
  18. 18.📏 Which unit measures current? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
  19. 19.🧮 A 3.2 V battery is joined to 12 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  20. 20.🔺 A current of 3 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) less than either one (c) their sum (d) always zero
  22. 22.🧩 Which component blows if current is high? (a) diode (b) fuse (c) resistor (d) potentiometer
  23. 23.True or false: the voltmeter measures current. (a) True (b) False
  24. 24.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) measure heat (d) store charge briefly
  25. 25.🔺 An 8 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  26. 26.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = R ÷ I (c) V = I × R (d) V = I + R
  27. 27.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  28. 28.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  29. 29.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  30. 30.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  32. 32.Which of these is measured in volts (V)? (a) power (b) the flow of charge (c) energy used each second (d) voltage
  33. 33.🔺 A 6.6 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  34. 34.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
  35. 35.🌈 A resistor has the colour bands yellow, blue, red. What is its value in kilo-ohms (kΩ)? =
  36. 36.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
  37. 37.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1000 Ω resistor? (a) brown-black-red (b) brown-black-brown (c) red-brown-red (d) brown-black-orange
  38. 38.What does a diode do? (a) makes a beeping sound (b) senses how bright it is (c) stores a little charge (d) lets current go one way
  39. 39.🌈 A resistor has the colour bands blue, red, red. What is its value in kilo-ohms (kΩ)? =
  40. 40.🔍 Which is the odd one out? (a) run fans in empty rooms (b) iron one shirt at a time (c) set the AC to 24 °C (d) leave fridge door open

Answer key

  1. 3
  2. 200
  3. set the AC to 24 °C
  4. 320
  5. 230
  6. 2.2
  7. 0.25
  8. wastes electricity
  9. 504
  10. 880
  11. 0.25
  12. 0
  13. 12
  14. 20
  15. cathode (−)
  16. 16.5
  17. False
  18. ampere (A)
  19. 0.2
  20. 24
  21. less than either one
  22. fuse
  23. False
  24. store charge briefly
  25. 40
  26. V = I × R
  27. cathode (−)
  28. True
  29. 1150
  30. 1.2
  31. ammeter
  32. voltage
  33. 20
  34. 4.8
  35. 4.6
  36. bigger
  37. brown-black-red
  38. lets current go one way
  39. 6.2
  40. set the AC to 24 °C

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