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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 294 · 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.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  2. 2.Which of these saves electricity? (a) use old filament bulbs (b) run fans in empty rooms (c) unplug idle chargers (d) leave the TV on standby
  3. 3.🔺 A current of 2 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  4. 4.🧮 Resistors of 220 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  5. 5.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) energy used each second (d) the size of a cell
  6. 6.📏 How many milliamperes (mA) is 0.86 A?
  7. 7.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  8. 8.🧾 A 100 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  9. 9.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) stays the same (d) becomes zero
  10. 10.🌈 In the resistor colour code, which number does brown stand for?
  11. 11.⚡ A 6 W device works on 24 V. What current does it take (in amperes)? =
  12. 12.True or false: the ammeter measures current. (a) False (b) True
  13. 13.🔺 A current of 10 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  15. 15.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a motor (d) a fuse
  16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 220 Ω resistor? (a) red-red-red (b) red-orange-brown (c) red-red-brown (d) red-red-black
  17. 17.🔺 A 6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  18. 18.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) their sum (d) less than either one
  19. 19.🔺 A current of 20 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  21. 21.🔺 A current of 10 mA flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  22. 22.Which of these saves electricity? (a) leave the TV on standby (b) leave fridge door open (c) iron one shirt at a time (d) use LED lamps
  23. 23.🔺 A current of 1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.📏 How many milliamperes (mA) is 0.01 A?
  25. 25.True or false: an LED glows using little power. (a) True (b) False
  26. 26.🔺 A 1.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  27. 27.🧮 A 20 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  28. 28.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.🧩 Which component smooths a wobbly supply? (a) transistor (b) capacitor (c) LDR (d) potentiometer
  32. 32.True or false: a potentiometer beeps for an alarm. (a) False (b) True
  33. 33.🔺 A current of 0.2 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.📏 How many kilo-ohms (kΩ) is 5900 Ω? =
  35. 35.🔺 A current of 0.2 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  36. 36.🔺 A 15 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  37. 37.🌈 In the resistor colour code, which number does violet stand for?
  38. 38.🔺 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
  39. 39.True or false: a buzzer beeps for an alarm. (a) False (b) True
  40. 40.🔺 A current of 50 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. cathode (−)
  2. unplug idle chargers
  3. 3
  4. 690
  5. energy used each second
  6. 860
  7. 110
  8. 0.4
  9. gets smaller
  10. 1
  11. 0.25
  12. True
  13. 4
  14. anode (+)
  15. a motor
  16. red-red-brown
  17. 2
  18. less than either one
  19. 2.4
  20. 1840
  21. 100
  22. use LED lamps
  23. 2
  24. 10
  25. True
  26. 0.5
  27. 40
  28. 30
  29. 20
  30. 0.2
  31. capacitor
  32. False
  33. 4
  34. 5.9
  35. 10
  36. 2.5
  37. 7
  38. I = V ÷ R
  39. True
  40. 25

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