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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 589 · 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.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  2. 2.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  3. 3.🔺 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
  4. 4.Which of these is measured in volts (V)? (a) the flow of charge (b) current (c) how much a part resists (d) the push of a cell
  5. 5.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.⚡ A 12 W device works on 12 V. What current does it take (in amperes)? =
  7. 7.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
  8. 8.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) stay the same (d) smaller
  9. 9.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  10. 10.True or false: the voltmeter is joined in series. (a) False (b) True
  11. 11.True or false: a motor lets current go one way. (a) False (b) True
  12. 12.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  13. 13.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🌈 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
  15. 15.🧮 Resistors of 100 Ω, 470 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  16. 16.🧮 Resistors of 470 Ω, 22 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  17. 17.📏 How many ohms (Ω) is 3.4 kΩ?
  18. 18.🧩 Which component senses how bright it is? (a) LED (b) potentiometer (c) transistor (d) LDR
  19. 19.📏 How many kilowatts (kW) is 400 W? =
  20. 20.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
  22. 22.🧮 A 10 V battery is joined to 5 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  23. 23.📏 How many milliamperes (mA) is 2.72 A?
  24. 24.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I
  26. 26.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the water pressure (c) the flow of water (d) the pipe colour
  27. 27.🧾 A 50 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  28. 28.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  30. 30.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
  31. 31.🔺 A current of 0.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🧮 Resistors of 20 Ω, 10 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  33. 33.🌈 A resistor has the colour bands green, black, red. What is its value in kilo-ohms (kΩ)? =
  34. 34.🔺 A current of 2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🧮 Resistors of 47 Ω, 10 Ω, 470 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  36. 36.🌈 A resistor has the colour bands red, yellow, red. What is its value in kilo-ohms (kΩ)? =
  37. 37.⚡ A 3 W device works on 12 V. What current does it take (in amperes)? =
  38. 38.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to change its colour (d) to make it brighter
  39. 39.True or false: a diode lets current go one way. (a) False (b) True
  40. 40.Which of these wastes electricity? (a) use LED lamps (b) switch off empty rooms (c) leave fridge door open (d) use daylight to read

Answer key

  1. True
  2. 165
  3. V = I × R
  4. the push of a cell
  5. 3.75
  6. 1
  7. gets smaller
  8. bigger
  9. 50
  10. False
  11. False
  12. 100
  13. 1
  14. the one nearest an end
  15. 670
  16. 525
  17. 3400
  18. LDR
  19. 0.4
  20. 100
  21. False
  22. 1
  23. 2720
  24. 0.75
  25. P = V × I
  26. the flow of water
  27. 0.1
  28. 2
  29. 230
  30. 0.1
  31. 2.5
  32. 50
  33. 5
  34. 20
  35. 595
  36. 2.4
  37. 0.25
  38. to limit the current
  39. True
  40. leave fridge door open

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