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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 113 · 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 resistor colour code, which number does brown stand for?
  2. 2.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  4. 4.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 100 (c) 10 (d) 1000
  5. 5.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  6. 6.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) bigger (d) zero
  8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 25000 Ω resistor? (a) red-green-yellow (b) green-red-orange (c) red-green-orange (d) red-green-red
  9. 9.🔺 A current of 1.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🌈 In the resistor colour code, which number does blue stand for?
  11. 11.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = V ÷ I (c) R = V + I (d) R = I ÷ V
  12. 12.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 93 Ω resistor? (a) orange-white-black (b) white-orange-brown (c) white-orange-black (d) brown-orange-black
  13. 13.🔺 A current of 20 mA flows when 8 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.True or false: a buzzer has coloured bands. (a) True (b) False
  15. 15.💡 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)?
  16. 16.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
  17. 17.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =
  18. 18.🔺 A 24 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  19. 19.🧩 Which component turns a fan or wheels? (a) capacitor (b) potentiometer (c) LDR (d) motor
  20. 20.📏 How many kilowatts (kW) is 1100 W? =
  21. 21.🔺 A 2 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  22. 22.🔺 A current of 1 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🔺 A current of 25 mA flows when 8.25 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🔺 A current of 0.5 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.🌈 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
  26. 26.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
  27. 27.True or false: on an LED, the longer leg is the cathode (−). (a) True (b) False
  28. 28.🧩 Which component boosts a small signal? (a) capacitor (b) transistor (c) buzzer (d) thermistor
  29. 29.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🧮 A 470 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  31. 31.🔺 A current of 0.2 A flows when 0.6 V is joined across a resistor. What is its resistance (in ohms)?
  32. 32.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.🧾 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?
  34. 34.🧮 A 33 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  35. 35.True or false: the push of a cell is measured in volts (V). (a) True (b) False
  36. 36.True or false: the ammeter is joined in series. (a) False (b) True
  37. 37.🔺 A current of 1.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the size of a cell (d) the length of a wire
  39. 39.🔺 A 60 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  40. 40.💡 An LED is joined to a 9 V battery through a 220 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

Answer key

  1. 1
  2. 250
  3. 2300
  4. 1000
  5. anode (+)
  6. 0.4
  7. bigger
  8. red-green-orange
  9. 6
  10. 6
  11. R = V ÷ I
  12. white-orange-black
  13. 400
  14. False
  15. 5
  16. False
  17. 3
  18. 2
  19. motor
  20. 1.1
  21. 0.5
  22. 4
  23. 330
  24. 5
  25. the one nearest an end
  26. P = V × I
  27. False
  28. transistor
  29. 0.6
  30. 635
  31. 3
  32. 2
  33. 315
  34. 38
  35. True
  36. True
  37. 5
  38. energy used each second
  39. 3
  40. lights up

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