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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 799 · 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.True or false: an LED boosts a small signal. (a) True (b) False
  2. 2.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  3. 3.⚡ A 0.75 W device works on 1.5 V. What current does it take (in amperes)? =
  4. 4.🔺 A 10 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  5. 5.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🔺 A 3 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  7. 7.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  8. 8.🔺 A 7.5 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  9. 9.⚡ A device works on 6 V and takes 2 A. What is its power (in watts)? =
  10. 10.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
  11. 11.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a motor (d) a resistor
  12. 12.⚡ A device works on 12 V and takes 2 A. What is its power (in watts)? =
  13. 13.🧮 A 4.5 V battery is joined to 6 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  14. 14.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.True or false: a fuse blows if current is high. (a) False (b) True
  16. 16.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  17. 17.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
  18. 18.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
  19. 19.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 19000 Ω resistor? (a) brown-white-yellow (b) brown-white-orange (c) brown-white-red (d) white-brown-orange
  22. 22.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
  23. 23.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
  24. 24.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  25. 25.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  26. 26.📏 How many amperes (A) is 1090 mA? =
  27. 27.What does a resistor do? (a) glows using little power (b) makes a beeping sound (c) limits the current (d) lets current go one way
  28. 28.🧮 Resistors of 22 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  29. 29.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  31. 31.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) spin a wheel (d) store charge briefly
  32. 32.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) the colour of light (d) energy used each second
  34. 34.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
  36. 36.🔍 Which is the odd one out? (a) leave fridge door open (b) use daylight to read (c) run fans in empty rooms (d) leave the TV on standby
  37. 37.📏 How many ohms (Ω) is 2.6 kΩ?
  38. 38.🔺 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
  39. 39.What does a motor do? (a) boosts a small signal (b) is a resistance knob (c) lets current go one way (d) turns a fan or wheels
  40. 40.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

Answer key

  1. False
  2. False
  3. 0.5
  4. 25
  5. 0.3
  6. 20
  7. voltmeter
  8. 25
  9. 12
  10. bigger
  11. a motor
  12. 24
  13. 0.5
  14. 100
  15. True
  16. 230
  17. 5 %
  18. 10
  19. 12
  20. 200
  21. brown-white-orange
  22. gets smaller
  23. P = V × I
  24. 20
  25. 460
  26. 1.09
  27. limits the current
  28. 42
  29. 20
  30. 1150
  31. store charge briefly
  32. 2.2
  33. energy used each second
  34. 2.5
  35. 34
  36. use daylight to read
  37. 2600
  38. V = I × R
  39. turns a fan or wheels
  40. 25

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