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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 196 · 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.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) ampere (A) (c) volt (V) (d) watt (W)
  2. 2.🧮 A 20 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  3. 3.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an LED lamp (d) an oil lamp
  4. 4.🔺 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
  5. 5.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🔺 A 20 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  7. 7.🧮 A 3.2 V battery is joined to 4 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 700 Ω resistor? (a) grey-violet-brown (b) violet-black-brown (c) violet-black-black (d) violet-black-red
  9. 9.🔍 Which is the odd one out? (a) switch off empty rooms (b) close the fridge quickly (c) use LED lamps (d) leave the TV on standby
  10. 10.📏 How many milliamperes (mA) is 2.4 A?
  11. 11.🔺 A current of 2 A flows when 40 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) less than either one (d) their sum
  13. 13.🧮 A 10 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  14. 14.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  15. 15.🔺 A current of 25 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.🌈 A resistor has the colour bands violet, white, red. What is its value (in ohms)?
  17. 17.True or false: a capacitor smooths a wobbly supply. (a) True (b) False
  18. 18.🔺 A 1.2 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  19. 19.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I ÷ R (d) V = I × R
  20. 20.True or false: the ammeter is joined in series. (a) False (b) True
  21. 21.🧾 A 100 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  22. 22.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
  23. 23.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
  24. 24.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 12000 Ω resistor? (a) red-brown-orange (b) brown-red-red (c) brown-red-orange (d) brown-red-yellow
  25. 25.🔺 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
  26. 26.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 9700 Ω resistor? (a) white-violet-red (b) violet-white-red (c) white-violet-orange (d) white-violet-brown
  27. 27.🧮 A 5 V battery is joined to 10 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  28. 28.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  30. 30.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) zero (c) bigger (d) stay the same
  31. 31.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  32. 32.🧮 A 3.2 V battery is joined to 12 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  33. 33.📏 How many milliamperes (mA) make 1 ampere? (a) 60 (b) 10 (c) 100 (d) 1000
  34. 34.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 0 % (d) 25 %
  35. 35.📏 How many amperes (A) is 410 mA? =
  36. 36.True or false: the ammeter measures voltage. (a) False (b) True
  37. 37.💡 Does it save or waste electricity to leave fridge door open? (a) wastes electricity (b) saves electricity
  38. 38.⚡ A device works on 12 V and takes 1.5 A. What is its power (in watts)? =
  39. 39.True or false: a capacitor stores a little charge. (a) True (b) False
  40. 40.🌈 A resistor has the colour bands red, blue, black. What is its value (in ohms)?

Answer key

  1. volt (V)
  2. 30
  3. an LED lamp
  4. I = V ÷ R
  5. 15
  6. 40
  7. 0.2
  8. violet-black-brown
  9. leave the TV on standby
  10. 2400
  11. 20
  12. less than either one
  13. 60
  14. may burn out
  15. 7.5
  16. 7900
  17. True
  18. 0.1
  19. V = I × R
  20. True
  21. 0.4
  22. 10
  23. 5
  24. brown-red-orange
  25. R = V ÷ I
  26. white-violet-red
  27. 0.25
  28. 20
  29. 5
  30. bigger
  31. 2300
  32. 0.2
  33. 1000
  34. 5 %
  35. 0.41
  36. False
  37. wastes electricity
  38. 18
  39. True
  40. 26

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