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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 748 · 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 current of 0.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  3. 3.🧾 A 200 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  4. 4.Which of these saves electricity? (a) iron one shirt at a time (b) use LED lamps (c) use old filament bulbs (d) leave fridge door open
  5. 5.⚡ A 3 W device works on 3 V. What current does it take (in amperes)? =
  6. 6.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
  7. 7.🔺 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
  8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 93 Ω resistor? (a) white-orange-black (b) white-orange-brown (c) brown-orange-black (d) orange-white-black
  9. 9.True or false: to set the AC to 24 °C saves electricity. (a) True (b) False
  10. 10.What does a resistor do? (a) has coloured bands (b) lets current go one way (c) smooths a wobbly supply (d) stores a little charge
  11. 11.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the pipe colour (c) the water pressure (d) the water tank lid
  13. 13.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🌈 In the resistor colour code, which number does yellow stand for?
  15. 15.🌈 A resistor has the colour bands grey, green, brown. What is its value (in ohms)?
  16. 16.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 1000 (c) 10 (d) 100
  17. 17.🌈 In the resistor colour code, which number does blue stand for?
  18. 18.🔺 A current of 1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
  20. 20.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  21. 21.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) gets bigger (d) stays the same
  22. 22.🧮 Resistors of 22 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  23. 23.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V + I (d) P = V ÷ I
  24. 24.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.🔺 A current of 1.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) make light (d) measure heat
  27. 27.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  28. 28.🔺 A 0.6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  29. 29.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.True or false: current is measured in amperes (A). (a) False (b) True
  31. 31.🔺 A current of 10 mA flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  33. 33.📏 How many amperes (A) is 2420 mA? =
  34. 34.🧮 A 0.8 V battery is joined to 3 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  35. 35.🔺 A current of 0.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.True or false: a thermistor limits the current. (a) False (b) True
  38. 38.🔺 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
  39. 39.What does an LED do? (a) turns a fan or wheels (b) glows using little power (c) senses how hot it is (d) makes a beeping sound
  40. 40.True or false: a potentiometer boosts a small signal. (a) True (b) False

Answer key

  1. 5
  2. 920
  3. 0.8
  4. use LED lamps
  5. 1
  6. 5
  7. V = I × R
  8. white-orange-black
  9. True
  10. has coloured bands
  11. 6
  12. the water pressure
  13. 15
  14. 4
  15. 850
  16. 1000
  17. 6
  18. 3
  19. 0.2
  20. False
  21. gets smaller
  22. 90
  23. P = V × I
  24. 3
  25. 4
  26. store charge briefly
  27. 10
  28. 0.2
  29. 7.5
  30. True
  31. 120
  32. 50
  33. 2.42
  34. 0.1
  35. 4
  36. 1.2
  37. False
  38. I = V ÷ R
  39. glows using little power
  40. False

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