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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 361 · 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 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.Which of these is measured in volts (V)? (a) the flow of charge (b) how much a part resists (c) the push of a cell (d) current
  3. 3.🔺 A current of 0.25 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🧮 An 11 V battery is joined to 5 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  5. 5.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) becomes zero (d) gets bigger
  6. 6.🧩 A capacitor in a circuit can … (a) spin a wheel (b) make light (c) measure heat (d) store charge briefly
  7. 7.Which of these wastes electricity? (a) set the AC to 24 °C (b) use LED lamps (c) use daylight to read (d) leave the TV on standby
  8. 8.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  9. 9.🌈 A resistor has the colour bands brown, grey, red. What is its value in kilo-ohms (kΩ)? =
  10. 10.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🔺 A 1.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  12. 12.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  13. 13.What does a resistor do? (a) senses how hot it is (b) beeps for an alarm (c) stores a little charge (d) limits the current
  14. 14.🧮 Resistors of 47 Ω, 470 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  15. 15.🌈 A resistor has the colour bands red, red, red. What is its value (in ohms)?
  16. 16.⚡ A device works on 6 V and takes 3 A. What is its power (in watts)? =
  17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1700 Ω resistor? (a) violet-brown-red (b) brown-violet-brown (c) brown-violet-red (d) brown-violet-orange
  18. 18.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
  19. 19.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  20. 20.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = I ÷ V (c) R = V ÷ I (d) R = V × I
  21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 380 Ω resistor? (a) orange-grey-black (b) orange-grey-brown (c) grey-orange-brown (d) orange-grey-red
  22. 22.💡 An LED is joined to a 6 V battery through a 1000 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
  23. 23.🔺 A 12.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  24. 24.💡 Does it save or waste electricity to leave fridge door open? (a) wastes electricity (b) saves electricity
  25. 25.🔺 A 30 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  26. 26.🌈 In the resistor colour code, which number does black stand for?
  27. 27.💡 Why does an LED need a resistor in series? (a) to store charge (b) to change its colour (c) to make it brighter (d) to limit the current
  28. 28.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
  29. 29.🔺 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
  30. 30.🔺 A current of 3 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🔺 An 8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  32. 32.True or false: an LED boosts a small signal. (a) False (b) True
  33. 33.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  34. 34.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = V ÷ I (d) P = I ÷ V
  35. 35.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  36. 36.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
  38. 38.What does a transistor do? (a) boosts a small signal (b) senses how bright it is (c) glows using little power (d) turns a fan or wheels
  39. 39.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  40. 40.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 2300 Ω resistor? (a) orange-red-red (b) red-orange-orange (c) red-orange-brown (d) red-orange-red

Answer key

  1. 8
  2. the push of a cell
  3. 5
  4. 1
  5. gets smaller
  6. store charge briefly
  7. leave the TV on standby
  8. 15
  9. 1.8
  10. 4
  11. 10
  12. 230
  13. limits the current
  14. 564
  15. 2200
  16. 18
  17. brown-violet-red
  18. True
  19. cathode (−)
  20. R = V ÷ I
  21. orange-grey-brown
  22. lights up
  23. 2.5
  24. wastes electricity
  25. 3
  26. 0
  27. to limit the current
  28. 1
  29. V = I × R
  30. 10
  31. 2
  32. False
  33. 40
  34. P = V × I
  35. voltmeter
  36. 330
  37. 10
  38. boosts a small signal
  39. 235
  40. red-orange-red

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