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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 894 · 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: a fuse blows if current is high. (a) True (b) False
  2. 2.📏 How many kilowatts (kW) is 3100 W? =
  3. 3.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  4. 4.🔺 An 18.8 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  5. 5.💡 An LED is joined to a 5 V battery with no 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
  6. 6.🌈 A resistor has the colour bands red, orange, yellow. What is its value in kilo-ohms (kΩ)? =
  7. 7.🌈 In the resistor colour code, which number does black stand for?
  8. 8.🧮 A 0.8 V battery is joined to 2 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  9. 9.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = V × I (d) P = I ÷ V
  10. 10.🌈 A resistor has the colour bands red, black, black. What is its value (in ohms)?
  11. 11.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
  12. 12.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the colour of light (d) the size of a cell
  13. 13.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🧮 Resistors of 20 Ω, 68 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  15. 15.🌈 A resistor has the colour bands violet, orange, black. What is its value (in ohms)?
  16. 16.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🔺 A current of 0.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.📏 How many milliamperes (mA) is 1.38 A?
  21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 900 Ω resistor? (a) white-black-red (b) white-black-black (c) white-black-brown (d) brown-white-brown
  22. 22.🔺 A current of 0.25 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  24. 24.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) the widest gap (d) any band
  25. 25.🧩 Which part changes electrical energy into movement? (a) an LED (b) a motor (c) a resistor (d) a fuse
  26. 26.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 5 % (c) 50 % (d) 0 %
  27. 27.True or false: energy used each second is measured in watts (W). (a) True (b) False
  28. 28.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 45 Ω resistor? (a) yellow-green-brown (b) green-green-black (c) yellow-green-black (d) green-yellow-black
  29. 29.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
  30. 30.🧮 Resistors of 68 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  31. 31.🧩 Which component limits the current? (a) resistor (b) potentiometer (c) LDR (d) diode
  32. 32.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.💡 A red LED uses 2 V and should get 25 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  34. 34.🔺 A current of 2 A flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.💡 An LED is joined to a 3 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) does not light (b) may burn out (c) lights up
  36. 36.🔺 A current of 10 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.🔺 A current of 20 mA flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.🌈 In the resistor colour code, which number does white stand for?
  39. 39.🧾 A 500 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
  40. 40.What does a motor do? (a) beeps for an alarm (b) boosts a small signal (c) makes things spin (d) glows using little power

Answer key

  1. True
  2. 3.1
  3. 1150
  4. 40
  5. may burn out
  6. 230
  7. 0
  8. 0.1
  9. P = V × I
  10. 20
  11. wastes electricity
  12. energy used each second
  13. 6
  14. 558
  15. 73
  16. 4
  17. 4
  18. 5
  19. 4
  20. 1380
  21. white-black-brown
  22. 2.5
  23. anode (+)
  24. the one nearest an end
  25. a motor
  26. 5 %
  27. True
  28. yellow-green-black
  29. False
  30. 101
  31. resistor
  32. 8
  33. 400
  34. 4
  35. does not light
  36. 200
  37. 300
  38. 9
  39. 5
  40. makes things spin

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