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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 897 · 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.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) zero (d) bigger
  2. 2.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the size of a cell (d) the colour of light
  3. 3.🧮 A 20 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  4. 4.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 0 % (d) 5 %
  5. 5.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  6. 6.Which of these saves electricity? (a) use old filament bulbs (b) run fans in empty rooms (c) close the fridge quickly (d) iron one shirt at a time
  7. 7.🧮 A 2.4 V battery is joined to 6 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  8. 8.💡 A red LED uses 2 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  9. 9.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  11. 11.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 330 Ω resistor? (a) orange-yellow-brown (b) orange-orange-red (c) orange-orange-black (d) orange-orange-brown
  12. 12.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
  15. 15.⚡ A device works on 9 V and takes 1 A. What is its power (in watts)? =
  16. 16.🔺 A 2 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  17. 17.🧾 A 1000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  18. 18.🔺 A current of 50 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.📏 Which unit measures current? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
  20. 20.Which of these is measured in amperes (A)? (a) the push of a cell (b) the flow of charge (c) voltage (d) how much a part resists
  21. 21.🌈 In the resistor colour code, which number does white stand for?
  22. 22.🔍 Which is the odd one out? (a) use old filament bulbs (b) leave the TV on standby (c) use daylight to read (d) leave fridge door open
  23. 23.🧩 Which component is a resistance knob? (a) motor (b) potentiometer (c) capacitor (d) LED
  24. 24.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) a filament bulb (d) an LED lamp
  25. 25.🔺 A current of 20 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.💡 An LED is joined to a 6 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) does not light (c) may burn out
  27. 27.📏 How many amperes (A) is 780 mA? =
  28. 28.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  29. 29.🌈 In the resistor colour code, which number does brown stand for?
  30. 30.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = R ÷ I (d) V = I × R
  31. 31.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V × I (d) P = V + I
  32. 32.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  33. 33.True or false: the voltmeter measures current. (a) False (b) True
  34. 34.🧾 A 200 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  35. 35.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 watt (c) 1 ampere (d) 1 kilowatt-hour (kWh)
  36. 36.🌈 A resistor has the colour bands grey, red, black. What is its value (in ohms)?
  37. 37.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  38. 38.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  39. 39.⚡ A 3 W device works on 1.5 V. What current does it take (in amperes)? =
  40. 40.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)

Answer key

  1. bigger
  2. energy used each second
  3. 520
  4. 5 %
  5. 5
  6. close the fridge quickly
  7. 0.2
  8. 160
  9. 1.2
  10. 100
  11. orange-orange-brown
  12. 2
  13. 2
  14. wastes electricity
  15. 9
  16. 0.5
  17. 4
  18. 23.5
  19. ampere (A)
  20. the flow of charge
  21. 9
  22. use daylight to read
  23. potentiometer
  24. an LED lamp
  25. 250
  26. lights up
  27. 0.78
  28. voltmeter
  29. 1
  30. V = I × R
  31. P = V × I
  32. 15
  33. False
  34. 1.6
  35. 1 kilowatt-hour (kWh)
  36. 82
  37. 345
  38. True
  39. 2
  40. cathode (−)

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