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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 32 · 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 200 Ω resistor. What current flows (in milliamperes, mA)?
  2. 2.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  3. 3.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  4. 4.⚡ A device works on 3 V and takes 0.2 A. What is its power (in watts)? =
  5. 5.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = V + I (d) P = I ÷ V
  6. 6.True or false: to iron one shirt at a time wastes electricity. (a) False (b) True
  7. 7.🔺 A current of 50 mA flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  9. 9.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  10. 10.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  11. 11.True or false: current is measured in ohms (Ω). (a) True (b) False
  12. 12.🔺 A 40 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  13. 13.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) less than either one (d) their sum
  14. 14.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
  15. 15.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  16. 16.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.📏 How many amperes (A) is 1360 mA? =
  18. 18.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.Which of these is measured in ohms (Ω)? (a) how much a part resists (b) voltage (c) the flow of charge (d) power
  20. 20.🔺 A 25 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  21. 21.🔺 An 8 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  22. 22.Which of these is measured in volts (V)? (a) current (b) energy used each second (c) the flow of charge (d) voltage
  23. 23.📏 Which unit measures the push of a cell? (a) ampere (A) (b) watt (W) (c) volt (V) (d) ohm (Ω)
  24. 24.🔺 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
  25. 25.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 100 (c) 1024 (d) 1000
  26. 26.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  27. 27.🔺 A 4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  28. 28.🔺 An 18.8 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.📏 Which unit measures current? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
  30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 36 Ω resistor? (a) yellow-blue-black (b) orange-blue-black (c) blue-orange-black (d) orange-blue-brown
  31. 31.💡 A red LED uses 2 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  32. 32.💡 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?
  33. 33.🌈 A resistor has the colour bands orange, white, orange. What is its value (in ohms)?
  34. 34.🔺 A current of 2 A flows when 24 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🔺 A current of 1.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🔺 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
  37. 37.🧩 Which part changes electrical energy into sound? (a) a diode (b) a buzzer (c) a resistor (d) a capacitor
  38. 38.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  40. 40.What does an LDR do? (a) beeps for an alarm (b) turns a fan or wheels (c) has coloured bands (d) senses how bright it is

Answer key

  1. 50
  2. 25
  3. 920
  4. 0.6
  5. P = V × I
  6. True
  7. 200
  8. 10
  9. cathode (−)
  10. True
  11. False
  12. 2
  13. less than either one
  14. store charge briefly
  15. False
  16. 0.2
  17. 1.36
  18. 5
  19. how much a part resists
  20. 50
  21. 40
  22. voltage
  23. volt (V)
  24. V = I × R
  25. 1000
  26. 0.1
  27. 2
  28. 40
  29. ampere (A)
  30. orange-blue-black
  31. 150
  32. 300
  33. 39000
  34. 12
  35. 4
  36. R = V ÷ I
  37. a buzzer
  38. 3
  39. anode (+)
  40. senses how bright it is

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