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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 760 · 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.

NameDateTime takenScore ___ / 40
  1. 1.True or false: to run fans in empty rooms saves electricity. (a) True (b) False
  2. 2.🌈 A resistor has the colour bands yellow, brown, red. What is its value in kilo-ohms (kΩ)? =
  3. 3.🔺 A current of 0.1 A flows when 0.8 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.🧮 A 1.8 V battery is joined to 3 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  5. 5.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.💡 A red LED uses 2 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  7. 7.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
  8. 8.🧮 Two equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  9. 9.⚡ A 6 W device works on 12 V. What current does it take (in amperes)? =
  10. 10.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) energy used each second (d) the size of a cell
  11. 11.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 25 % (d) 50 %
  12. 12.🧩 Which component blows if current is high? (a) fuse (b) diode (c) resistor (d) LDR
  13. 13.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
  14. 14.🌈 Which band is read first on a resistor? (a) the widest gap (b) any band (c) the one nearest an end (d) the gold band
  15. 15.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) smaller (d) stay the same
  16. 16.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  17. 17.🔺 A 15 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  18. 18.🌈 In the resistor colour code, which number does red stand for?
  19. 19.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  20. 20.🔺 A 1 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  21. 21.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.🔺 A current of 25 mA flows when 12.5 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🧾 A 1500 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  24. 24.📏 How many kilowatts (kW) is 1250 W? =
  25. 25.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) stays the same (c) becomes zero (d) gets bigger
  26. 26.🌈 In the resistor colour code, which number does blue stand for?
  27. 27.⚡ A 36 W device works on 12 V. What current does it take (in amperes)? =
  28. 28.Which of these saves electricity? (a) leave the TV on standby (b) close the fridge quickly (c) iron one shirt at a time (d) leave fridge door open
  29. 29.📏 How many kilo-ohms (kΩ) is 9000 Ω? =
  30. 30.📏 Which unit measures how much a part resists? (a) watt (W) (b) volt (V) (c) ampere (A) (d) ohm (Ω)
  31. 31.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  32. 32.⚡ A 4.5 W device works on 3 V. What current does it take (in amperes)? =
  33. 33.🔺 A 4 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  34. 34.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.What does a fuse do? (a) is a resistance knob (b) limits the current (c) stores a little charge (d) blows if current is high
  36. 36.📏 How many watts (W) is 1.2 kW?
  37. 37.Which of these saves electricity? (a) leave the TV on standby (b) iron one shirt at a time (c) switch off empty rooms (d) use old filament bulbs
  38. 38.💡 An LED is joined to a 6 V battery through a 470 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
  39. 39.💡 A red LED uses 2 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  40. 40.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?

Answer key

  1. False
  2. 4.1
  3. 8
  4. 0.2
  5. 3
  6. 500
  7. saves electricity
  8. 50
  9. 0.5
  10. energy used each second
  11. 5 %
  12. fuse
  13. 5
  14. the one nearest an end
  15. bigger
  16. 5
  17. 1.5
  18. 2
  19. lights up
  20. 0.25
  21. 6
  22. 500
  23. 9
  24. 1.25
  25. gets smaller
  26. 6
  27. 3
  28. close the fridge quickly
  29. 9
  30. ohm (Ω)
  31. 460
  32. 1.5
  33. 1
  34. 0.3
  35. blows if current is high
  36. 1200
  37. switch off empty rooms
  38. lights up
  39. 700
  40. 10

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