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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 273 · 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.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  2. 2.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  3. 3.⚡ A device works on 5 V and takes 0.1 A. What is its power (in watts)? =
  4. 4.🌈 Which band is read first on a resistor? (a) any band (b) the gold band (c) the widest gap (d) the one nearest an end
  5. 5.🔺 A current of 1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.Which of these is measured in watts (W)? (a) energy used each second (b) current (c) how much a part resists (d) voltage
  7. 7.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a filament bulb (c) a candle (d) an LED lamp
  8. 8.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
  9. 9.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) smaller (d) zero
  10. 10.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🧩 Which component senses how bright it is? (a) transistor (b) potentiometer (c) LDR (d) diode
  12. 12.🌈 A resistor has the colour bands yellow, black, red. What is its value in kilo-ohms (kΩ)? =
  13. 13.🧮 Resistors of 470 Ω, 20 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  14. 14.Which of these is measured in amperes (A)? (a) power (b) energy used each second (c) current (d) resistance
  15. 15.True or false: the push of a cell is measured in volts (V). (a) False (b) True
  16. 16.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  17. 17.True or false: energy used each second is measured in watts (W). (a) False (b) True
  18. 18.🔺 A 1.2 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  19. 19.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =
  20. 20.🌈 A resistor has the colour bands violet, white, orange. What is its value (in ohms)?
  21. 21.🔺 A current of 0.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.True or false: the flow of charge is measured in amperes (A). (a) False (b) True
  23. 23.🔺 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
  24. 24.📏 How many ohms (Ω) is 2.1 kΩ?
  25. 25.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
  26. 26.📏 How many ohms (Ω) is 5.8 kΩ?
  27. 27.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.📏 How many milliamperes (mA) is 1.25 A?
  29. 29.📏 How many amperes (A) is 1030 mA? =
  30. 30.💡 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)?
  31. 31.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.Which of these is measured in ohms (Ω)? (a) energy used each second (b) resistance (c) power (d) the push of a cell
  33. 33.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the colour of light (d) the length of a wire
  34. 34.🔺 A current of 1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🧩 Which component blows if current is high? (a) resistor (b) potentiometer (c) fuse (d) diode
  36. 36.🔺 A 3 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  37. 37.True or false: to iron one shirt at a time saves electricity. (a) True (b) False
  38. 38.True or false: a motor blows if current is high. (a) True (b) False
  39. 39.True or false: a capacitor turns a fan or wheels. (a) True (b) False
  40. 40.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True

Answer key

  1. True
  2. 200
  3. 0.5
  4. the one nearest an end
  5. 10
  6. energy used each second
  7. an LED lamp
  8. 5 %
  9. bigger
  10. 15
  11. LDR
  12. 4
  13. 820
  14. current
  15. True
  16. 0.2
  17. True
  18. 10
  19. 0.3
  20. 79000
  21. 7.5
  22. True
  23. I = V ÷ R
  24. 2100
  25. saves electricity
  26. 5800
  27. 0.4
  28. 1250
  29. 1.03
  30. 15
  31. 0.8
  32. resistance
  33. energy used each second
  34. 20
  35. fuse
  36. 0.5
  37. False
  38. False
  39. False
  40. False

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