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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 80 · 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.🧮 Resistors of 470 Ω, 33 Ω, 22 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  2. 2.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  3. 3.True or false: a buzzer makes a beeping sound. (a) True (b) False
  4. 4.True or false: the ammeter measures voltage. (a) True (b) False
  5. 5.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
  6. 6.🔺 A current of 3 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the size of a cell (d) the colour of light
  8. 8.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V ÷ I (c) R = V × I (d) R = I ÷ V
  9. 9.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) their sum (d) always zero
  10. 10.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  11. 11.True or false: to set the AC to 24 °C wastes electricity. (a) True (b) False
  12. 12.🧩 Which component glows using little power? (a) LDR (b) thermistor (c) fuse (d) LED
  13. 13.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  14. 14.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  15. 15.🧾 Which lamp gives the same light for the least power? (a) a candle (b) a filament bulb (c) an oil lamp (d) an LED lamp
  16. 16.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
  17. 17.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  18. 18.🔺 A current of 40 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  19. 19.🔺 A current of 2 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🔺 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
  21. 21.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  22. 22.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
  23. 23.🔺 A current of 20 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.Which of these is measured in amperes (A)? (a) resistance (b) energy used each second (c) how much a part resists (d) current
  25. 25.🔺 A current of 1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  27. 27.📏 How many ohms (Ω) is 3.9 kΩ?
  28. 28.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.True or false: the voltmeter is joined across a part. (a) True (b) False
  30. 30.🌈 In the resistor colour code, which number does orange stand for?
  31. 31.🌈 In the resistor colour code, which number does black stand for?
  32. 32.🧮 A 1.4 V battery is joined to 2 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  33. 33.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 74 Ω resistor? (a) yellow-violet-black (b) violet-yellow-brown (c) grey-yellow-black (d) violet-yellow-black
  36. 36.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
  37. 37.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  38. 38.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.🧮 A 3 V battery is joined to 6 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  40. 40.🧾 A 50 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =

Answer key

  1. 575
  2. 360
  3. True
  4. False
  5. 0.75
  6. 36
  7. energy used each second
  8. R = V ÷ I
  9. less than either one
  10. 50
  11. False
  12. LED
  13. 100
  14. voltmeter
  15. an LED lamp
  16. 5 %
  17. 100
  18. 100
  19. 5
  20. V = I × R
  21. 1150
  22. 1.5
  23. 200
  24. current
  25. 10
  26. cathode (−)
  27. 3900
  28. 25
  29. True
  30. 3
  31. 0
  32. 0.2
  33. 8.25
  34. 8
  35. violet-yellow-black
  36. 4.8
  37. 460
  38. 330
  39. 0.25
  40. 0.3

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