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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 947 · 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: a transistor boosts a small signal. (a) False (b) True
  2. 2.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
  3. 3.🧮 A 22 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  4. 4.What does a potentiometer do? (a) is a resistance knob (b) has coloured bands (c) makes things spin (d) limits the current
  5. 5.🧾 A 200 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  6. 6.Which of these saves electricity? (a) iron one shirt at a time (b) close the fridge quickly (c) run fans in empty rooms (d) leave the TV on standby
  7. 7.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V ÷ R (c) I = V × R (d) I = R ÷ V
  8. 8.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) a motor (d) an LED
  9. 9.Which of these saves electricity? (a) run fans in empty rooms (b) leave fridge door open (c) use daylight to read (d) leave the TV on standby
  10. 10.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V ÷ I (d) P = V × I
  11. 11.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the one nearest an end (d) the widest gap
  13. 13.True or false: a potentiometer limits the current. (a) False (b) True
  14. 14.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  15. 15.🔺 A current of 40 mA flows when 13.2 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  17. 17.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
  18. 18.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
  19. 19.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) always zero (c) their sum (d) more than either one
  21. 21.🌈 A resistor has the colour bands grey, yellow, red. What is its value (in ohms)?
  22. 22.⚡ A device works on 6 V and takes 0.5 A. What is its power (in watts)? =
  23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 35 Ω resistor? (a) orange-green-brown (b) green-orange-black (c) orange-green-black (d) yellow-green-black
  24. 24.What does an LED do? (a) boosts a small signal (b) glows using little power (c) turns a fan or wheels (d) beeps for an alarm
  25. 25.🧮 A 150 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  26. 26.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  27. 27.🧮 A 3 V battery is joined to 3 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  28. 28.🧮 Resistors of 22 Ω, 68 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  29. 29.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 2 hours. How many watt-hours (Wh) are saved?
  31. 31.Which of these saves electricity? (a) leave the TV on standby (b) switch off empty rooms (c) use old filament bulbs (d) leave fridge door open
  32. 32.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 5 % (d) 50 %
  33. 33.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  34. 34.🔺 A 6 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  35. 35.What does a thermistor do? (a) glows using little power (b) turns a fan or wheels (c) senses how hot it is (d) boosts a small signal
  36. 36.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
  37. 37.🧾 A 1500 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  38. 38.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.🔺 A 24 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  40. 40.🔺 A 12 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?

Answer key

  1. True
  2. False
  3. 122
  4. is a resistance knob
  5. 1.6
  6. close the fridge quickly
  7. I = V ÷ R
  8. a motor
  9. use daylight to read
  10. P = V × I
  11. 10
  12. the one nearest an end
  13. False
  14. 5
  15. 330
  16. 20
  17. wastes electricity
  18. store charge briefly
  19. 9.4
  20. less than either one
  21. 8400
  22. 3
  23. orange-green-black
  24. glows using little power
  25. 260
  26. True
  27. 0.2
  28. 123
  29. 0.4
  30. 102
  31. switch off empty rooms
  32. 5 %
  33. cathode (−)
  34. 1.5
  35. senses how hot it is
  36. bigger
  37. 12
  38. 3
  39. 3
  40. 40

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