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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 732 · 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 20 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  2. 2.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) light-emitting diode (d) large electric dial
  3. 3.🔺 A 0.3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  4. 4.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the gold band (d) the one nearest an end
  5. 5.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
  6. 6.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) bigger (c) stay the same (d) zero
  7. 7.🔺 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
  8. 8.💡 An LED is joined to a 9 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
  9. 9.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) an LED lamp (d) a filament bulb
  10. 10.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) store charge briefly (d) spin a wheel
  11. 11.🧮 A 4 V battery is joined to 4 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  12. 12.Which of these is measured in volts (V)? (a) voltage (b) power (c) energy used each second (d) current
  13. 13.⚡ A 3 W device works on 6 V. What current does it take (in amperes)? =
  14. 14.🧩 Which component senses how hot it is? (a) motor (b) LDR (c) thermistor (d) capacitor
  15. 15.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  16. 16.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = R ÷ I (d) V = I × R
  17. 17.🔺 A 5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  18. 18.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
  19. 19.🧩 Which component beeps for an alarm? (a) thermistor (b) LED (c) fuse (d) buzzer
  20. 20.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 50 % (d) 0 %
  21. 21.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  22. 22.🔺 A current of 2.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  24. 24.🌈 A resistor has the colour bands red, red, red. What is its value (in ohms)?
  25. 25.🔺 A current of 0.2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.🔺 A 2.5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  27. 27.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🧩 Which part changes electrical energy into sound? (a) a diode (b) a capacitor (c) a buzzer (d) a resistor
  29. 29.🔺 An 18 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  30. 30.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  31. 31.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
  32. 32.🌈 A resistor has the colour bands green, white, red. What is its value in kilo-ohms (kΩ)? =
  33. 33.🔺 A current of 0.1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.Which of these saves electricity? (a) unplug idle chargers (b) leave the TV on standby (c) iron one shirt at a time (d) leave fridge door open
  35. 35.⚡ A device works on 6 V and takes 0.2 A. What is its power (in watts)? =
  36. 36.📏 Which unit measures the flow of charge? (a) volt (V) (b) ohm (Ω) (c) ampere (A) (d) watt (W)
  37. 37.📏 Which unit measures resistance? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
  38. 38.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  39. 39.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) always zero (d) more than either one

Answer key

  1. 2.5
  2. light-emitting diode
  3. 0.1
  4. the one nearest an end
  5. P = V × I
  6. bigger
  7. R = V ÷ I
  8. does not light
  9. an LED lamp
  10. store charge briefly
  11. 0.25
  12. voltage
  13. 0.5
  14. thermistor
  15. 40
  16. V = I × R
  17. 0.5
  18. True
  19. buzzer
  20. 5 %
  21. 20
  22. 50
  23. 50
  24. 2200
  25. 3
  26. 0.25
  27. 1.5
  28. a buzzer
  29. 1.5
  30. 500
  31. True
  32. 5.9
  33. 0.6
  34. unplug idle chargers
  35. 1.2
  36. ampere (A)
  37. ohm (Ω)
  38. 2300
  39. 12
  40. less than either one

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