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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 718 · 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.📏 How many kilo-ohms (kΩ) is 600 Ω? =
  2. 2.True or false: a buzzer senses how hot it is. (a) False (b) True
  3. 3.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
  5. 5.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
  6. 6.Which of these saves electricity? (a) leave the TV on standby (b) run fans in empty rooms (c) use old filament bulbs (d) set the AC to 24 °C
  7. 7.🧾 A 500 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  8. 8.⚡ A device works on 6 V and takes 3 A. What is its power (in watts)? =
  9. 9.📏 How many amperes (A) is 1210 mA? =
  10. 10.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 5 V supply. What current flows (in mA)?
  11. 11.🌈 A resistor has the colour bands grey, green, red. What is its value (in ohms)?
  12. 12.🔺 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
  13. 13.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 4.25 V supply. What current flows (in mA)?
  14. 14.🧮 A 100 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  15. 15.What does a diode do? (a) senses how bright it is (b) stores a little charge (c) glows using little power (d) lets current go one way
  16. 16.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 10 (c) 100 (d) 1000
  17. 17.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  18. 18.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  19. 19.📏 Which unit measures how much a part resists? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
  20. 20.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) energy used each second (d) the size of a cell
  22. 22.📏 How many watts (W) is 0.5 kW?
  23. 23.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  24. 24.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) bigger (d) stay the same
  25. 25.🔺 A current of 3 A flows when 9 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.Which of these is measured in volts (V)? (a) how much a part resists (b) power (c) energy used each second (d) the push of a cell
  27. 27.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  28. 28.🌈 A resistor has the colour bands brown, green, red. What is its value (in ohms)?
  29. 29.🧮 Resistors of 220 Ω, 47 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  30. 30.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  31. 31.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  32. 32.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  33. 33.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.💡 Does it save or waste electricity to run fans in empty rooms? (a) saves electricity (b) wastes electricity
  36. 36.🌈 A resistor has the colour bands green, violet, red. What is its value in kilo-ohms (kΩ)? =
  37. 37.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  38. 38.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
  39. 39.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I × R (c) V = I + R (d) V = I ÷ R
  40. 40.🌈 A resistor has the colour bands brown, brown, red. What is its value in kilo-ohms (kΩ)? =

Answer key

  1. 0.6
  2. False
  3. 20
  4. P = V × I
  5. 5 %
  6. set the AC to 24 °C
  7. 2
  8. 18
  9. 1.21
  10. 20
  11. 8500
  12. I = V ÷ R
  13. 15
  14. 600
  15. lets current go one way
  16. 1000
  17. 10
  18. cathode (−)
  19. ohm (Ω)
  20. 2.5
  21. energy used each second
  22. 500
  23. anode (+)
  24. bigger
  25. 3
  26. the push of a cell
  27. 460
  28. 1500
  29. 317
  30. voltmeter
  31. 1150
  32. 20
  33. 0.5
  34. 7.5
  35. wastes electricity
  36. 5.7
  37. ammeter
  38. 5
  39. V = I × R
  40. 1.1

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