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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 673 · 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 2.4 W device works on 12 V. What current does it take (in amperes)? =
  2. 2.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = R ÷ V (c) I = V + R (d) I = V × R
  3. 3.🔍 Which is the odd one out? (a) use old filament bulbs (b) use daylight to read (c) use LED lamps (d) close the fridge quickly
  4. 4.🧮 A 47 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)?
  5. 5.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) energy used each second (d) the colour of light
  6. 6.🔺 A current of 3 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
  8. 8.📏 How many ohms (Ω) is 4 kΩ?
  9. 9.⚡ A 72 W device works on 24 V. What current does it take (in amperes)? =
  10. 10.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) less than either one (d) their sum
  11. 11.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = I ÷ V (d) P = V ÷ I
  13. 13.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = V × I (c) R = I ÷ V (d) R = V ÷ I
  14. 14.🌈 A resistor has the colour bands grey, white, red. What is its value (in ohms)?
  15. 15.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a fuse (d) a motor
  16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 92 Ω resistor? (a) brown-red-black (b) red-white-black (c) white-red-black (d) white-red-brown
  17. 17.True or false: voltage is measured in volts (V). (a) False (b) True
  18. 18.🔺 A current of 40 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
  19. 19.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  20. 20.🌈 A resistor has the colour bands red, yellow, brown. What is its value (in ohms)?
  21. 21.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  23. 23.📏 How many kilo-ohms (kΩ) is 8800 Ω? =
  24. 24.🔍 Which is the odd one out? (a) leave fridge door open (b) use LED lamps (c) use daylight to read (d) switch off empty rooms
  25. 25.🔺 A current of 2 A flows when 16 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🔺 A current of 1 A flows when 10 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 71 Ω resistor? (a) grey-brown-black (b) violet-brown-brown (c) violet-brown-black (d) brown-violet-black
  28. 28.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 400 Ω resistor? (a) green-yellow-brown (b) yellow-black-red (c) yellow-black-brown (d) yellow-black-black
  29. 29.🔺 A 3 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  30. 30.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
  31. 31.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  33. 33.🔺 A current of 0.25 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.📏 Which unit measures energy used each second? (a) ampere (A) (b) ohm (Ω) (c) watt (W) (d) volt (V)
  35. 35.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to change its colour (d) to make it brighter
  36. 36.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
  37. 37.🧩 Which component lets current go one way? (a) LED (b) buzzer (c) diode (d) fuse
  38. 38.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1000 (b) 100 (c) 10 (d) 1024
  39. 39.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  40. 40.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter

Answer key

  1. 0.2
  2. I = V ÷ R
  3. use old filament bulbs
  4. 67
  5. energy used each second
  6. 4
  7. 5
  8. 4000
  9. 3
  10. less than either one
  11. 2
  12. P = V × I
  13. R = V ÷ I
  14. 8900
  15. a motor
  16. white-red-black
  17. True
  18. 500
  19. voltmeter
  20. 240
  21. 16
  22. 345
  23. 8.8
  24. leave fridge door open
  25. 8
  26. 10
  27. violet-brown-black
  28. yellow-black-brown
  29. 0.25
  30. True
  31. 12
  32. 15
  33. 8
  34. watt (W)
  35. to limit the current
  36. 0.75
  37. diode
  38. 1000
  39. 120
  40. voltmeter

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