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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 508 · 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.

NameDateTime takenScore ___ / 40
  1. 1.🧩 Which component smooths a wobbly supply? (a) thermistor (b) potentiometer (c) capacitor (d) diode
  2. 2.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  3. 3.📏 How many kilo-ohms (kΩ) is 3000 Ω? =
  4. 4.🔺 A 2.5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  5. 5.🧾 A 500 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  6. 6.📏 Which unit measures the push of a cell? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
  7. 7.True or false: the voltmeter is joined across a part. (a) True (b) False
  8. 8.📏 Which unit measures power? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
  9. 9.⚡ A 48 W device works on 24 V. What current does it take (in amperes)? =
  10. 10.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 25 % (d) 50 %
  11. 11.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  12. 12.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  13. 13.⚡ A device works on 1.5 V and takes 1.5 A. What is its power (in watts)? =
  14. 14.🌈 In the resistor colour code, which number does brown stand for?
  15. 15.🧩 Which component beeps for an alarm? (a) LDR (b) resistor (c) buzzer (d) diode
  16. 16.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🔺 A current of 2.5 A flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  19. 19.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  20. 20.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) stays the same (d) becomes zero
  21. 21.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) zero (d) bigger
  22. 22.🧩 Which component senses how hot it is? (a) fuse (b) thermistor (c) potentiometer (d) LED
  23. 23.🔺 A 15 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  24. 24.True or false: a diode has coloured bands. (a) True (b) False
  25. 25.🧮 A 470 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)?
  26. 26.🧩 Which part changes electrical energy into movement? (a) a resistor (b) a fuse (c) a motor (d) an LED
  27. 27.🧮 A 3.5 V battery is joined to 5 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  28. 28.🌈 A resistor has the colour bands brown, grey, red. What is its value (in ohms)?
  29. 29.🔺 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
  30. 30.🔺 A current of 2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧮 A 3.2 V battery is joined to 12 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  32. 32.🌈 A resistor has the colour bands white, black, orange. What is its value (in ohms)?
  33. 33.🔺 A current of 0.25 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.🔺 A 4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  36. 36.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.Which of these wastes electricity? (a) run fans in empty rooms (b) set the AC to 24 °C (c) switch off empty rooms (d) unplug idle chargers
  38. 38.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.🧮 Two resistors in parallel give a total that is … (a) their sum (b) less than either one (c) always zero (d) more than either one

Answer key

  1. capacitor
  2. ammeter
  3. 3
  4. 25
  5. 2
  6. volt (V)
  7. True
  8. watt (W)
  9. 2
  10. 5 %
  11. 10
  12. 1150
  13. 2.25
  14. 1
  15. buzzer
  16. 9
  17. 1.25
  18. 10
  19. 200
  20. gets smaller
  21. bigger
  22. thermistor
  23. 1.5
  24. False
  25. 705
  26. a motor
  27. 0.5
  28. 1800
  29. V = I × R
  30. 40
  31. 0.2
  32. 90000
  33. 5
  34. 120
  35. 1
  36. 1.2
  37. run fans in empty rooms
  38. 6
  39. 12
  40. less than either one

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