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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 417 · 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.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  2. 2.🌈 A resistor has the colour bands orange, white, orange. What is its value (in ohms)?
  3. 3.🧩 Which part changes electrical energy into movement? (a) an LED (b) a fuse (c) a resistor (d) a motor
  4. 4.💡 What does LED stand for? (a) light energy dial (b) large electric dial (c) light-emitting diode (d) low energy device
  5. 5.🌈 In the resistor colour code, which number does brown stand for?
  6. 6.⚡ 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
  7. 7.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a resistor (c) a diode (d) a capacitor
  8. 8.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  9. 9.True or false: a fuse makes a beeping sound. (a) False (b) True
  10. 10.📏 How many kilo-ohms (kΩ) is 6700 Ω? =
  11. 11.🌈 A resistor has the colour bands orange, brown, red. What is its value in kilo-ohms (kΩ)? =
  12. 12.🌈 A resistor has the colour bands orange, red, red. What is its value in kilo-ohms (kΩ)? =
  13. 13.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) less than either one (d) always zero
  14. 14.True or false: to leave the TV on standby wastes electricity. (a) False (b) True
  15. 15.🔺 A current of 50 mA flows when 11 V is joined across a resistor. What is its resistance (in ohms)?
  16. 16.🔺 A current of 25 mA flows when 11.75 V is joined across a resistor. What is its resistance (in ohms)?
  17. 17.🔺 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
  18. 18.📏 How many ohms (Ω) is 4.6 kΩ?
  19. 19.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 5 % (d) 25 %
  20. 20.⚡ A 1.2 W device works on 6 V. What current does it take (in amperes)? =
  21. 21.True or false: a buzzer beeps for an alarm. (a) False (b) True
  22. 22.🧩 Which component beeps for an alarm? (a) LDR (b) capacitor (c) buzzer (d) motor
  23. 23.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  24. 24.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  25. 25.🔺 A current of 25 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.🔍 Which is the odd one out? (a) iron one shirt at a time (b) close the fridge quickly (c) switch off empty rooms (d) unplug idle chargers
  27. 27.📏 How many milliamperes (mA) is 1.14 A?
  28. 28.True or false: a diode senses how hot it is. (a) False (b) True
  29. 29.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  30. 30.💡 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)?
  31. 31.🔺 A current of 3 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🌈 A resistor has the colour bands orange, green, black. What is its value (in ohms)?
  33. 33.🧮 Resistors of 22 Ω, 100 Ω, 330 Ω and 47 Ω are joined in series. What is the total resistance (in ohms)?
  34. 34.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🔺 A current of 0.1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  37. 37.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) any band (d) the widest gap
  38. 38.🌈 A resistor has the colour bands brown, yellow, orange. What is its value (in ohms)?
  39. 39.📏 How many milliamperes (mA) is 1.83 A?
  40. 40.🔺 A current of 0.1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 2
  2. 39000
  3. a motor
  4. light-emitting diode
  5. 1
  6. energy used each second
  7. a buzzer
  8. 10
  9. False
  10. 6.7
  11. 3.1
  12. 3.2
  13. less than either one
  14. True
  15. 220
  16. 470
  17. V = I × R
  18. 4600
  19. 5 %
  20. 0.2
  21. True
  22. buzzer
  23. cathode (−)
  24. 230
  25. 11.75
  26. iron one shirt at a time
  27. 1140
  28. False
  29. cathode (−)
  30. 10
  31. 60
  32. 35
  33. 499
  34. 6
  35. 2
  36. voltmeter
  37. the one nearest an end
  38. 14000
  39. 1830
  40. 0.3

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