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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 853 · 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 6 W device works on 6 V. What current does it take (in amperes)? =
  2. 2.📏 Which unit measures resistance? (a) ohm (Ω) (b) watt (W) (c) volt (V) (d) ampere (A)
  3. 3.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = I × R (d) V = R ÷ I
  4. 4.🔺 A 4 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  5. 5.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 25 % (d) 0 %
  7. 7.🧮 A 3.6 V battery is joined to 6 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  8. 8.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  9. 9.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 watt
  10. 10.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
  11. 11.Which of these saves electricity? (a) run fans in empty rooms (b) iron one shirt at a time (c) use LED lamps (d) use old filament bulbs
  12. 12.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water tank lid (c) the tap handle (d) the water pressure
  13. 13.🧩 Which component boosts a small signal? (a) potentiometer (b) fuse (c) transistor (d) resistor
  14. 14.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
  15. 15.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.🧩 Which component beeps for an alarm? (a) LED (b) potentiometer (c) buzzer (d) capacitor
  17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 790 Ω resistor? (a) violet-white-red (b) violet-white-black (c) white-violet-brown (d) violet-white-brown
  18. 18.Which of these is measured in ohms (Ω)? (a) energy used each second (b) how much a part resists (c) the flow of charge (d) power
  19. 19.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) their sum (d) more than either one
  20. 20.⚡ A device works on 5 V and takes 1.5 A. What is its power (in watts)? =
  21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 13 Ω resistor? (a) brown-orange-black (b) brown-orange-brown (c) orange-brown-black (d) red-orange-black
  22. 22.🌈 In the resistor colour code, which number does green stand for?
  23. 23.🌈 A resistor has the colour bands brown, green, orange. What is its value (in ohms)?
  24. 24.🔺 A current of 0.25 A flows when 0.5 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.📏 Which unit measures the push of a cell? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
  26. 26.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  28. 28.True or false: a resistor has coloured bands. (a) False (b) True
  29. 29.🔺 A 0.5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  30. 30.⚡ A device works on 5 V and takes 3 A. What is its power (in watts)? =
  31. 31.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) smaller (d) zero
  32. 32.🌈 A resistor has the colour bands green, white, red. What is its value (in ohms)?
  33. 33.True or false: a transistor senses how bright it is. (a) True (b) False
  34. 34.🧩 Which component makes a beeping sound? (a) buzzer (b) LDR (c) transistor (d) capacitor
  35. 35.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
  36. 36.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) energy used each second (d) the size of a cell
  37. 37.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light-emitting diode (d) light energy dial
  38. 38.🔺 A current of 2.5 A flows through a 20 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.True or false: a buzzer blows if current is high. (a) False (b) True

Answer key

  1. 1
  2. ohm (Ω)
  3. V = I × R
  4. 0.2
  5. 5
  6. 5 %
  7. 0.2
  8. 345
  9. 1 kilowatt-hour (kWh)
  10. gets smaller
  11. use LED lamps
  12. the water pressure
  13. transistor
  14. 5
  15. 12
  16. buzzer
  17. violet-white-brown
  18. how much a part resists
  19. less than either one
  20. 7.5
  21. brown-orange-black
  22. 5
  23. 15000
  24. 2
  25. volt (V)
  26. 120
  27. 115
  28. True
  29. 0.25
  30. 15
  31. bigger
  32. 5900
  33. False
  34. buzzer
  35. P = V × I
  36. energy used each second
  37. light-emitting diode
  38. 50
  39. anode (+)
  40. False

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