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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 281 · 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.True or false: a fuse blows if current is high. (a) False (b) True
  2. 2.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  3. 3.💡 What happens if an LED is put in backwards? (a) it does not light (b) it changes colour (c) it makes a sound (d) it lights brighter
  4. 4.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  5. 5.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V × I (d) P = V ÷ I
  6. 6.True or false: how much a part resists is measured in ohms (Ω). (a) False (b) True
  7. 7.🔺 A 4.7 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  8. 8.🔺 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
  9. 9.🔺 A 7.5 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  10. 10.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 1000 (c) 10 (d) 60
  11. 11.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) leave the TV on standby (c) use daylight to read (d) switch off empty rooms
  12. 12.🧮 A 1.1 V battery is joined to 5 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  13. 13.🔺 A current of 25 mA flows when 11.75 V is joined across a resistor. What is its resistance (in ohms)?
  14. 14.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  15. 15.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  16. 16.🧮 A 1.6 V battery is joined to 2 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  17. 17.🧮 A 2 V battery is joined to 4 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  18. 18.📏 In the water-pipe picture of a circuit, current is like … (a) the pipe colour (b) the flow of water (c) a narrow pipe (d) the water pressure
  19. 19.🔺 A current of 1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.True or false: an LED makes a beeping sound. (a) True (b) False
  21. 21.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V ÷ R (c) I = V × R (d) I = V + R
  22. 22.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 8200 Ω resistor? (a) grey-red-red (b) grey-red-orange (c) grey-red-brown (d) red-grey-red
  23. 23.🔺 A current of 50 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🧮 A 7 V battery is joined to 2 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  25. 25.True or false: current is measured in amperes (A). (a) True (b) False
  26. 26.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 56 Ω resistor? (a) green-blue-brown (b) blue-green-black (c) blue-blue-black (d) green-blue-black
  28. 28.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.True or false: the push of a cell is measured in amperes (A). (a) False (b) True
  30. 30.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  31. 31.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  32. 32.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  33. 33.🧮 A 15 V battery is joined to 12 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  34. 34.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  35. 35.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  36. 36.🔺 A current of 20 mA flows when 4.4 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.What does a potentiometer do? (a) makes a beeping sound (b) has coloured bands (c) is a resistance knob (d) smooths a wobbly supply
  38. 38.📏 How many watts (W) is 1.5 kW?
  39. 39.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
  40. 40.True or false: to unplug idle chargers saves electricity. (a) False (b) True

Answer key

  1. True
  2. 100
  3. it does not light
  4. 165
  5. P = V × I
  6. True
  7. 10
  8. R = V ÷ I
  9. 25
  10. 1000
  11. leave the TV on standby
  12. 0.1
  13. 470
  14. 200
  15. 25
  16. 0.2
  17. 0.2
  18. the flow of water
  19. 12
  20. False
  21. I = V ÷ R
  22. grey-red-red
  23. 150
  24. 1
  25. True
  26. 250
  27. green-blue-black
  28. 40
  29. False
  30. voltmeter
  31. anode (+)
  32. 1840
  33. 1
  34. 15
  35. 900
  36. 220
  37. is a resistance knob
  38. 1500
  39. ammeter
  40. True

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