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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 872 · 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 2000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  2. 2.🔺 A current of 1 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.🧮 A 1.75 V battery is joined to 4 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  4. 4.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the size of a cell (d) the length of a wire
  5. 5.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) how much a part resists (c) voltage (d) the push of a cell
  6. 6.🧮 Resistors of 50 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
  7. 7.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  8. 8.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
  10. 10.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) bigger (d) smaller
  11. 11.📏 How many milliamperes (mA) is 2.12 A?
  12. 12.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V ÷ R (c) I = R ÷ V (d) I = V + R
  13. 13.🧮 A 150 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  14. 14.🔺 A 1.2 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  15. 15.🔍 Which is the odd one out? (a) switch off empty rooms (b) unplug idle chargers (c) use LED lamps (d) iron one shirt at a time
  16. 16.True or false: the voltmeter measures current. (a) True (b) False
  17. 17.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.📏 Which unit measures resistance? (a) volt (V) (b) watt (W) (c) ohm (Ω) (d) ampere (A)
  19. 19.🔺 A current of 25 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.📏 How many kilowatts (kW) is 4850 W? =
  21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 820 Ω resistor? (a) grey-red-red (b) red-grey-brown (c) grey-red-black (d) grey-red-brown
  22. 22.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🧾 A 1500 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  24. 24.Which of these is measured in watts (W)? (a) resistance (b) energy used each second (c) voltage (d) how much a part resists
  25. 25.What does a capacitor do? (a) limits the current (b) glows using little power (c) smooths a wobbly supply (d) makes a beeping sound
  26. 26.🧮 A 330 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)?
  27. 27.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🧩 Which component beeps for an alarm? (a) diode (b) capacitor (c) resistor (d) buzzer
  29. 29.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 5 % (d) 25 %
  30. 30.Which of these wastes electricity? (a) unplug idle chargers (b) switch off empty rooms (c) leave the TV on standby (d) set the AC to 24 °C
  31. 31.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  32. 32.🔺 A current of 0.25 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.🧾 A 1500 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
  34. 34.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  35. 35.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
  36. 36.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
  38. 38.📏 How many milliamperes (mA) is 1.64 A?
  39. 39.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  40. 40.🔍 Which is the odd one out? (a) leave fridge door open (b) leave the TV on standby (c) run fans in empty rooms (d) use LED lamps

Answer key

  1. 8
  2. 15
  3. 0.25
  4. energy used each second
  5. how much a part resists
  6. 150
  7. anode (+)
  8. 0.2
  9. 238
  10. bigger
  11. 2120
  12. I = V ÷ R
  13. 155
  14. 0.1
  15. iron one shirt at a time
  16. False
  17. 330
  18. ohm (Ω)
  19. 6.25
  20. 4.85
  21. grey-red-brown
  22. 2
  23. 9
  24. energy used each second
  25. smooths a wobbly supply
  26. 565
  27. 1.5
  28. buzzer
  29. 5 %
  30. leave the TV on standby
  31. voltmeter
  32. 2
  33. 15
  34. cathode (−)
  35. 20
  36. 1.5
  37. 20
  38. 1640
  39. 115
  40. use LED lamps

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