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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 9 · 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 10 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  2. 2.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  3. 3.🔺 A current of 40 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) less than either one (d) more than either one
  5. 5.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.⚡ A 0.5 W device works on 5 V. What current does it take (in amperes)? =
  7. 7.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the flow of water (c) the water pressure (d) a narrow pipe
  9. 9.🧾 Which lamp gives the same light for the least power? (a) a candle (b) an LED lamp (c) an oil lamp (d) a filament bulb
  10. 10.🔺 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
  11. 11.🧩 Which component beeps for an alarm? (a) buzzer (b) LDR (c) LED (d) fuse
  12. 12.What does a diode do? (a) glows using little power (b) lets current go one way (c) has coloured bands (d) turns a fan or wheels
  13. 13.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  14. 14.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the colour of light (d) the length of a wire
  15. 15.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  16. 16.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  17. 17.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🧮 A 330 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  19. 19.🔺 A current of 50 mA flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.Which of these wastes electricity? (a) set the AC to 24 °C (b) unplug idle chargers (c) leave fridge door open (d) switch off empty rooms
  21. 21.What does a resistor do? (a) makes a beeping sound (b) has coloured bands (c) beeps for an alarm (d) glows using little power
  22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 82 Ω resistor? (a) white-red-black (b) red-grey-black (c) grey-red-brown (d) grey-red-black
  23. 23.📏 How many kilowatts (kW) is 1700 W? =
  24. 24.Which of these saves electricity? (a) set the AC to 24 °C (b) leave the TV on standby (c) iron one shirt at a time (d) leave fridge door open
  25. 25.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  26. 26.🔺 A 3 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  27. 27.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  28. 28.⚡ A device works on 6 V and takes 1 A. What is its power (in watts)? =
  29. 29.🔺 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
  30. 30.Which of these is measured in amperes (A)? (a) the push of a cell (b) current (c) how much a part resists (d) power
  31. 31.⚡ A device works on 1.5 V and takes 0.5 A. What is its power (in watts)? =
  32. 32.🔺 A current of 20 mA flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  33. 33.🧩 Which component stores a little charge? (a) LED (b) motor (c) capacitor (d) potentiometer
  34. 34.True or false: to unplug idle chargers wastes electricity. (a) False (b) True
  35. 35.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🔺 A 6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  37. 37.What does a fuse do? (a) boosts a small signal (b) blows if current is high (c) senses how hot it is (d) senses how bright it is
  38. 38.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  39. 39.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🔺 A current of 50 mA flows when 16.5 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

  1. 20
  2. 10
  3. 8
  4. less than either one
  5. 8
  6. 0.1
  7. 2
  8. a narrow pipe
  9. an LED lamp
  10. I = V ÷ R
  11. buzzer
  12. lets current go one way
  13. cathode (−)
  14. energy used each second
  15. 10
  16. 0.1
  17. 11.75
  18. 380
  19. 300
  20. leave fridge door open
  21. has coloured bands
  22. grey-red-black
  23. 1.7
  24. set the AC to 24 °C
  25. True
  26. 10
  27. 1840
  28. 6
  29. V = I × R
  30. current
  31. 0.75
  32. 200
  33. capacitor
  34. False
  35. 1
  36. 1
  37. blows if current is high
  38. True
  39. 120
  40. 330

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