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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 499 · 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.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an oil lamp (c) an LED lamp (d) a candle
  2. 2.🧮 A 220 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  3. 3.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
  5. 5.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 10 (c) 100 (d) 1024
  6. 6.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  7. 7.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) their sum (d) more than either one
  8. 8.⚡ A device works on 6 V and takes 0.5 A. What is its power (in watts)? =
  9. 9.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  10. 10.📏 Which unit measures the push of a cell? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
  11. 11.⚡ A device works on 24 V and takes 0.25 A. What is its power (in watts)? =
  12. 12.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🧮 A 22 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  14. 14.🧮 A 10 V battery is joined to 6 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  15. 15.Which of these wastes electricity? (a) unplug idle chargers (b) close the fridge quickly (c) switch off empty rooms (d) iron one shirt at a time
  16. 16.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
  17. 17.⚡ An 18 W device works on 9 V. What current does it take (in amperes)? =
  18. 18.Which of these is measured in volts (V)? (a) the push of a cell (b) current (c) resistance (d) the flow of charge
  19. 19.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) an LED (d) a motor
  20. 20.🔺 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
  21. 21.🔺 A 9.4 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  22. 22.⚡ A 3 W device works on 12 V. What current does it take (in amperes)? =
  23. 23.⚡ A device works on 9 V and takes 0.2 A. What is its power (in watts)? =
  24. 24.⚡ A device works on 24 V and takes 0.5 A. What is its power (in watts)? =
  25. 25.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) any band (d) the gold band
  26. 26.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  27. 27.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🌈 A resistor has the colour bands orange, green, brown. What is its value (in ohms)?
  31. 31.What does a resistor do? (a) has coloured bands (b) makes things spin (c) lets current go one way (d) senses how bright it is
  32. 32.⚡ A device works on 9 V and takes 0.25 A. What is its power (in watts)? =
  33. 33.🔺 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
  34. 34.What does a transistor do? (a) is a resistance knob (b) senses how bright it is (c) makes a beeping sound (d) boosts a small signal
  35. 35.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
  37. 37.True or false: a buzzer lets current go one way. (a) False (b) True
  38. 38.🔺 A current of 0.25 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  39. 39.💡 An LED is joined to a 5 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
  40. 40.🔺 A 6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =

Answer key

  1. an LED lamp
  2. 225
  3. 4.5
  4. False
  5. 1000
  6. cathode (−)
  7. less than either one
  8. 3
  9. 300
  10. volt (V)
  11. 6
  12. 2
  13. 187
  14. 1
  15. iron one shirt at a time
  16. 0.3
  17. 2
  18. the push of a cell
  19. a motor
  20. V = I × R
  21. 20
  22. 0.25
  23. 1.8
  24. 12
  25. the one nearest an end
  26. 50
  27. 2.4
  28. 20
  29. 2
  30. 350
  31. has coloured bands
  32. 2.25
  33. I = V ÷ R
  34. boosts a small signal
  35. 2
  36. False
  37. False
  38. 8
  39. may burn out
  40. 1

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