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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 621 · 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.🌈 In the resistor colour code, which number does yellow stand for?
  2. 2.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = I ÷ V (c) P = V × I (d) P = V + I
  3. 3.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to store charge (d) to make it brighter
  4. 4.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  5. 5.💡 An LED is joined to a 5 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  6. 6.🧮 A 150 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  7. 7.Which of these saves electricity? (a) set the AC to 24 °C (b) iron one shirt at a time (c) leave fridge door open (d) use old filament bulbs
  8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 78000 Ω resistor? (a) violet-grey-red (b) violet-grey-yellow (c) violet-grey-orange (d) grey-violet-orange
  9. 9.🧾 A 500 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  10. 10.🔺 A current of 0.1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  13. 13.🔺 A current of 40 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 86 Ω resistor? (a) white-blue-black (b) grey-blue-black (c) blue-grey-black (d) grey-blue-brown
  15. 15.⚡ A 3 W device works on 6 V. What current does it take (in amperes)? =
  16. 16.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.Which of these saves electricity? (a) use old filament bulbs (b) unplug idle chargers (c) run fans in empty rooms (d) leave fridge door open
  18. 18.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the colour of light (d) the size of a cell
  19. 19.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
  20. 20.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  21. 21.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  22. 22.📏 Which unit measures voltage? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
  23. 23.🧮 Resistors of 470 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  24. 24.🔍 Which is the odd one out? (a) unplug idle chargers (b) use LED lamps (c) set the AC to 24 °C (d) leave fridge door open
  25. 25.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the water tank lid (c) the tap handle (d) the pipe colour
  26. 26.🔺 A current of 50 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a buzzer (d) a capacitor
  28. 28.🌈 A resistor has the colour bands red, brown, orange. What is its value in kilo-ohms (kΩ)? =
  29. 29.🌈 A resistor has the colour bands green, brown, black. What is its value (in ohms)?
  30. 30.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🔺 A current of 20 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🧮 Resistors of 470 Ω, 22 Ω, 47 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  33. 33.📏 How many watts (W) is 2.9 kW?
  34. 34.⚡ A device works on 24 V and takes 1 A. What is its power (in watts)? =
  35. 35.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
  36. 36.🧾 A 1500 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
  37. 37.🔺 A 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  38. 38.📏 How many milliamperes (mA) is 2.64 A?
  39. 39.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.🔺 A 1.2 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =

Answer key

  1. 4
  2. P = V × I
  3. to limit the current
  4. 2300
  5. lights up
  6. 175
  7. set the AC to 24 °C
  8. violet-grey-orange
  9. 1
  10. 1
  11. 2.5
  12. 230
  13. 13.2
  14. grey-blue-black
  15. 0.5
  16. 1.2
  17. unplug idle chargers
  18. energy used each second
  19. 5 %
  20. 100
  21. cathode (−)
  22. volt (V)
  23. 538
  24. leave fridge door open
  25. the water pressure
  26. 25
  27. a buzzer
  28. 21
  29. 51
  30. 1.5
  31. 4
  32. 589
  33. 2900
  34. 24
  35. gets smaller
  36. 15
  37. 0.25
  38. 2640
  39. 1.5
  40. 0.1

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