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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 246 · 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 2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  2. 2.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🌈 A resistor has the colour bands green, black, orange. What is its value (in ohms)?
  4. 4.🧩 Which component senses how bright it is? (a) diode (b) LED (c) transistor (d) LDR
  5. 5.Which of these is measured in watts (W)? (a) resistance (b) how much a part resists (c) current (d) power
  6. 6.🧮 Resistors of 50 Ω, 33 Ω, 220 Ω and 22 Ω are joined in series. What is the total resistance (in ohms)?
  7. 7.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 64 Ω resistor? (a) blue-yellow-brown (b) yellow-blue-black (c) blue-yellow-black (d) violet-yellow-black
  8. 8.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) the size of a cell (d) energy used each second
  9. 9.🌈 In the resistor colour code, which number does grey stand for?
  10. 10.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  11. 11.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = R ÷ V (c) I = V + R (d) I = V ÷ R
  12. 12.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
  13. 13.🔺 A current of 25 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.🔺 A current of 0.25 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  16. 16.Which of these wastes electricity? (a) close the fridge quickly (b) use daylight to read (c) set the AC to 24 °C (d) use old filament bulbs
  17. 17.🧮 Resistors of 10 Ω, 220 Ω, 10 Ω and 150 Ω are joined in series. What is the total resistance (in ohms)?
  18. 18.Which of these saves electricity? (a) switch off empty rooms (b) leave fridge door open (c) leave the TV on standby (d) run fans in empty rooms
  19. 19.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  20. 20.🔺 A current of 1.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.💡 An LED is joined to a 12 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  22. 22.📏 How many kilowatts (kW) is 3300 W? =
  23. 23.💡 What does LED stand for? (a) light energy dial (b) large electric dial (c) light-emitting diode (d) low energy device
  24. 24.🧮 Resistors of 22 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  25. 25.🌈 In the resistor colour code, which number does violet stand for?
  26. 26.🧮 A 22 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  27. 27.📏 How many ohms (Ω) is 2.6 kΩ?
  28. 28.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  29. 29.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🧮 Resistors of 330 Ω, 100 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  31. 31.🌈 A resistor has the colour bands yellow, red, orange. What is its value (in ohms)?
  32. 32.📏 How many kilo-ohms (kΩ) is 1800 Ω? =
  33. 33.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  34. 34.Which of these saves electricity? (a) leave the TV on standby (b) leave fridge door open (c) use LED lamps (d) use old filament bulbs
  35. 35.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
  36. 36.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 14000 Ω resistor? (a) brown-yellow-yellow (b) yellow-brown-orange (c) brown-yellow-red (d) brown-yellow-orange
  37. 37.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V × I (c) P = V + I (d) P = I ÷ V
  39. 39.True or false: a resistor limits the current. (a) True (b) False
  40. 40.True or false: the voltmeter measures current. (a) True (b) False

Answer key

  1. 1
  2. 7.5
  3. 50000
  4. LDR
  5. power
  6. 325
  7. blue-yellow-black
  8. energy used each second
  9. 8
  10. 345
  11. I = V ÷ R
  12. 0.1
  13. 300
  14. 3.75
  15. True
  16. use old filament bulbs
  17. 390
  18. switch off empty rooms
  19. cathode (−)
  20. 10
  21. may burn out
  22. 3.3
  23. light-emitting diode
  24. 492
  25. 7
  26. 42
  27. 2600
  28. 920
  29. 20
  30. 900
  31. 42000
  32. 1.8
  33. cathode (−)
  34. use LED lamps
  35. saves electricity
  36. brown-yellow-orange
  37. 10
  38. P = V × I
  39. True
  40. False

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