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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 105 · 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 V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = I ÷ V (c) R = V × I (d) R = V + I
  2. 2.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  4. 4.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  5. 5.🧩 Which part changes electrical energy into sound? (a) a diode (b) a resistor (c) a buzzer (d) a capacitor
  6. 6.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
  7. 7.📏 In the water-pipe picture of a circuit, resistance is like … (a) the water pressure (b) a bigger tank (c) a narrow pipe (d) the flow of water
  8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7900 Ω resistor? (a) violet-white-red (b) violet-white-brown (c) white-violet-red (d) violet-white-orange
  9. 9.📏 How many ohms (Ω) is 1.9 kΩ?
  10. 10.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🧮 Resistors of 330 Ω, 330 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  12. 12.🔺 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
  13. 13.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  14. 14.🧮 A 220 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)?
  15. 15.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) zero (c) smaller (d) bigger
  16. 16.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
  17. 17.🧩 Which component smooths a wobbly supply? (a) LDR (b) capacitor (c) diode (d) resistor
  18. 18.Which of these is measured in volts (V)? (a) current (b) the flow of charge (c) how much a part resists (d) voltage
  19. 19.🌈 A resistor has the colour bands yellow, violet, red. What is its value in kilo-ohms (kΩ)? =
  20. 20.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  21. 21.🔺 A current of 0.1 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.Which of these saves electricity? (a) leave fridge door open (b) leave the TV on standby (c) use daylight to read (d) run fans in empty rooms
  23. 23.Which of these is measured in ohms (Ω)? (a) the push of a cell (b) voltage (c) how much a part resists (d) energy used each second
  24. 24.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity
  25. 25.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  27. 27.🔺 A current of 0.25 A flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
  28. 28.🔺 A 25 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.True or false: a capacitor stores a little charge. (a) False (b) True
  30. 30.What does a diode do? (a) makes things spin (b) lets current go one way (c) smooths a wobbly supply (d) senses how bright it is
  31. 31.⚡ A 3 W device works on 6 V. What current does it take (in amperes)? =
  32. 32.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) any band (d) the one nearest an end
  33. 33.🔺 A 10 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  34. 34.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 0 % (d) 50 %
  35. 35.💡 An LED is joined to a 9 V battery through a 1000 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
  36. 36.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  37. 37.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
  38. 38.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
  39. 39.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
  40. 40.🔺 A current of 1.5 A flows when 15 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

  1. R = V ÷ I
  2. 3.75
  3. cathode (−)
  4. voltmeter
  5. a buzzer
  6. P = V × I
  7. a narrow pipe
  8. violet-white-red
  9. 1900
  10. 12
  11. 1130
  12. V = I × R
  13. lights up
  14. 720
  15. bigger
  16. energy used each second
  17. capacitor
  18. voltage
  19. 4.7
  20. 10
  21. 12
  22. use daylight to read
  23. how much a part resists
  24. saves electricity
  25. 3
  26. 5
  27. 15
  28. 50
  29. True
  30. lets current go one way
  31. 0.5
  32. the one nearest an end
  33. 0.5
  34. 5 %
  35. does not light
  36. 12
  37. 4.8
  38. saves electricity
  39. True
  40. 10

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