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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 131 · 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.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 64 Ω resistor? (a) violet-yellow-black (b) yellow-blue-black (c) blue-yellow-black (d) blue-yellow-brown
  2. 2.⚡ A 9 W device works on 3 V. What current does it take (in amperes)? =
  3. 3.True or false: a buzzer beeps for an alarm. (a) True (b) False
  4. 4.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
  5. 5.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  7. 7.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  8. 8.🔺 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
  9. 9.🔺 A current of 50 mA flows when 11 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.⚡ A device works on 5 V and takes 0.25 A. What is its power (in watts)? =
  11. 11.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = R ÷ V (c) I = V ÷ R (d) I = V × R
  12. 12.🔺 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
  13. 13.🔺 A current of 20 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
  15. 15.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  16. 16.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
  17. 17.🔺 An 18 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  18. 18.🔺 A current of 0.25 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🔺 A current of 1 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) gets smaller (d) stays the same
  21. 21.🧩 Which component smooths a wobbly supply? (a) LDR (b) resistor (c) transistor (d) capacitor
  22. 22.🧮 A 2.4 V battery is joined to 6 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  23. 23.What does a transistor do? (a) smooths a wobbly supply (b) boosts a small signal (c) senses how hot it is (d) makes things spin
  24. 24.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.🌈 A resistor has the colour bands brown, red, orange. What is its value in kilo-ohms (kΩ)? =
  26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 420 Ω resistor? (a) red-yellow-brown (b) yellow-red-black (c) yellow-red-red (d) yellow-red-brown
  27. 27.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  28. 28.🌈 A resistor has the colour bands blue, orange, black. What is its value (in ohms)?
  29. 29.🔺 A 4 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  30. 30.💡 Does it save or waste electricity to leave the TV on standby? (a) wastes electricity (b) saves electricity
  31. 31.🧮 A 10 Ω resistor is joined in series with two equal 470 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  32. 32.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.💡 Does it save or waste electricity to leave fridge door open? (a) wastes electricity (b) saves electricity
  34. 34.True or false: a resistor turns a fan or wheels. (a) False (b) True
  35. 35.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) smaller (d) zero
  36. 36.What does a capacitor do? (a) stores a little charge (b) turns a fan or wheels (c) glows using little power (d) has coloured bands
  37. 37.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) store charge briefly (d) spin a wheel
  38. 38.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  39. 39.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  40. 40.True or false: a transistor boosts a small signal. (a) False (b) True

Answer key

  1. blue-yellow-black
  2. 3
  3. True
  4. a motor
  5. 0.4
  6. cathode (−)
  7. 600
  8. V = I × R
  9. 220
  10. 1.25
  11. I = V ÷ R
  12. R = V ÷ I
  13. 5
  14. 4.5
  15. anode (+)
  16. False
  17. 1.5
  18. 3
  19. 12
  20. gets smaller
  21. capacitor
  22. 0.2
  23. boosts a small signal
  24. 2.5
  25. 12
  26. yellow-red-brown
  27. 50
  28. 63
  29. 0.5
  30. wastes electricity
  31. 245
  32. 0.3
  33. wastes electricity
  34. False
  35. bigger
  36. stores a little charge
  37. store charge briefly
  38. 1840
  39. ammeter
  40. True

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