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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 963 · 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 part changes electrical energy into sound? (a) a diode (b) a capacitor (c) a buzzer (d) a resistor
  2. 2.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) the colour of light (d) energy used each second
  3. 3.🧩 Which component blows if current is high? (a) fuse (b) transistor (c) thermistor (d) LDR
  4. 4.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) their sum (c) more than either one (d) always zero
  5. 5.True or false: the voltmeter is joined across a part. (a) False (b) True
  6. 6.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  7. 7.Which of these saves electricity? (a) leave the TV on standby (b) run fans in empty rooms (c) use old filament bulbs (d) use daylight to read
  8. 8.🔍 Which is the odd one out? (a) use old filament bulbs (b) switch off empty rooms (c) set the AC to 24 °C (d) use daylight to read
  9. 9.🧮 Resistors of 150 Ω, 100 Ω, 470 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  10. 10.🌈 Which band is read first on a resistor? (a) any band (b) the widest gap (c) the one nearest an end (d) the gold band
  11. 11.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
  12. 12.🔺 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
  13. 13.💡 An LED is joined to a 6 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) does not light (c) may burn out
  14. 14.📏 In the water-pipe picture of a circuit, current is like … (a) the flow of water (b) the pipe colour (c) the water pressure (d) a narrow pipe
  15. 15.True or false: to run fans in empty rooms saves electricity. (a) True (b) False
  16. 16.True or false: how much a part resists is measured in volts (V). (a) True (b) False
  17. 17.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  18. 18.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🌈 In the resistor colour code, which number does black stand for?
  20. 20.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) an LED lamp (c) a candle (d) an oil lamp
  21. 21.⚡ A device works on 24 V and takes 0.5 A. What is its power (in watts)? =
  22. 22.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
  23. 23.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
  24. 24.Which of these wastes electricity? (a) use daylight to read (b) unplug idle chargers (c) switch off empty rooms (d) leave fridge door open
  25. 25.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  26. 26.🔺 A 2.4 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  27. 27.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 5 hours. How many watt-hours (Wh) are saved?
  29. 29.🔺 A current of 25 mA flows when 8.25 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.What does a buzzer do? (a) stores a little charge (b) makes a beeping sound (c) limits the current (d) makes things spin
  32. 32.🧮 A 10 V battery is joined to 4 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  33. 33.🔺 A 4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  34. 34.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) bigger (d) zero
  35. 35.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water tank lid (c) the water pressure (d) the tap handle
  36. 36.📏 How many milliamperes (mA) is 1.35 A?
  37. 37.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 0 % (d) 5 %
  38. 38.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 540 Ω resistor? (a) green-yellow-black (b) green-yellow-red (c) green-yellow-brown (d) yellow-green-brown
  39. 39.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  40. 40.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter

Answer key

  1. a buzzer
  2. energy used each second
  3. fuse
  4. less than either one
  5. True
  6. voltmeter
  7. use daylight to read
  8. use old filament bulbs
  9. 740
  10. the one nearest an end
  11. True
  12. V = I × R
  13. lights up
  14. the flow of water
  15. False
  16. False
  17. 5
  18. 16
  19. 0
  20. an LED lamp
  21. 12
  22. P = V × I
  23. 5
  24. leave fridge door open
  25. anode (+)
  26. 20
  27. 1.2
  28. 315
  29. 330
  30. 6
  31. makes a beeping sound
  32. 1
  33. 2
  34. bigger
  35. the water pressure
  36. 1350
  37. 5 %
  38. green-yellow-brown
  39. voltmeter
  40. ammeter

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