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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 775 · 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.🧮 Resistors of 20 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  2. 2.🔺 A 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  3. 3.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.📏 How many kilowatts (kW) is 4150 W? =
  5. 5.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 0 % (d) 25 %
  6. 6.🔺 A 15 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  7. 7.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V × I (d) P = V + I
  8. 8.True or false: voltage is measured in volts (V). (a) True (b) False
  9. 9.🔺 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
  10. 10.Which of these saves electricity? (a) switch off empty rooms (b) run fans in empty rooms (c) iron one shirt at a time (d) leave fridge door open
  11. 11.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
  12. 12.💡 What does LED stand for? (a) large electric dial (b) light energy dial (c) light-emitting diode (d) low energy device
  13. 13.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) zero (d) smaller
  14. 14.📏 Which unit measures the flow of charge? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
  15. 15.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =
  16. 16.🧩 Which component senses how bright it is? (a) capacitor (b) LED (c) LDR (d) motor
  17. 17.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  18. 18.True or false: an LED limits the current. (a) False (b) True
  19. 19.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  20. 20.🔺 A current of 1.5 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  22. 22.🔺 A current of 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water pressure (c) the water tank lid (d) the pipe colour
  24. 24.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) any band (d) the one nearest an end
  25. 25.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  26. 26.Which of these saves electricity? (a) iron one shirt at a time (b) use old filament bulbs (c) leave the TV on standby (d) use LED lamps
  27. 27.🔺 A 6.6 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  28. 28.🔺 A current of 0.25 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.True or false: a potentiometer has coloured bands. (a) True (b) False
  30. 30.🔺 A current of 50 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🧮 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
  33. 33.Which of these is measured in volts (V)? (a) resistance (b) current (c) voltage (d) energy used each second
  34. 34.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🔺 A 3 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  36. 36.⚡ A device works on 5 V and takes 3 A. What is its power (in watts)? =
  37. 37.True or false: a motor turns a fan or wheels. (a) False (b) True
  38. 38.📏 How many kilowatts (kW) is 2150 W? =
  39. 39.🧾 A 100 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  40. 40.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

  1. 120
  2. 0.2
  3. 1.5
  4. 4.15
  5. 5 %
  6. 50
  7. P = V × I
  8. True
  9. V = I × R
  10. switch off empty rooms
  11. store charge briefly
  12. light-emitting diode
  13. bigger
  14. ampere (A)
  15. 0.15
  16. LDR
  17. True
  18. False
  19. 460
  20. 8
  21. 80
  22. 18
  23. the water pressure
  24. the one nearest an end
  25. 25
  26. use LED lamps
  27. 20
  28. 20
  29. False
  30. 11
  31. 6
  32. less than either one
  33. voltage
  34. 0.75
  35. 1.5
  36. 15
  37. True
  38. 2.15
  39. 0.2
  40. 120

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