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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 128 · 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.

NameDateTime takenScore ___ / 40
  1. 1.What does a fuse do? (a) beeps for an alarm (b) makes things spin (c) makes a beeping sound (d) blows if current is high
  2. 2.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🌈 A resistor has the colour bands green, brown, red. What is its value (in ohms)?
  5. 5.True or false: to use old filament bulbs saves electricity. (a) False (b) True
  6. 6.True or false: the push of a cell is measured in volts (V). (a) True (b) False
  7. 7.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 66000 Ω resistor? (a) blue-violet-orange (b) blue-blue-red (c) blue-blue-yellow (d) blue-blue-orange
  9. 9.True or false: a potentiometer limits the current. (a) True (b) False
  10. 10.🔺 A 5 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  11. 11.🧮 A 3 V battery is joined to 4 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  12. 12.🔺 A current of 40 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  14. 14.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) energy used each second (d) the length of a wire
  15. 15.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = I × R (d) V = R ÷ I
  16. 16.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  17. 17.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
  18. 18.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  19. 19.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.🧮 A 470 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)?
  21. 21.💡 Does it save or waste electricity to unplug idle chargers? (a) saves electricity (b) wastes electricity
  22. 22.🌈 A resistor has the colour bands yellow, green, red. What is its value in kilo-ohms (kΩ)? =
  23. 23.🧮 A 47 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  24. 24.🔺 A current of 0.25 A flows when 0.75 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.🌈 A resistor has the colour bands white, black, brown. What is its value (in ohms)?
  26. 26.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  27. 27.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🔺 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
  29. 29.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to store charge (c) to limit the current (d) to change its colour
  30. 30.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  31. 31.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  32. 32.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets smaller (d) gets bigger
  33. 33.🧮 A 20 V battery is joined to 10 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  34. 34.🌈 A resistor has the colour bands violet, blue, red. What is its value in kilo-ohms (kΩ)? =
  35. 35.True or false: current is measured in amperes (A). (a) False (b) True
  36. 36.Which of these is measured in watts (W)? (a) power (b) voltage (c) resistance (d) the push of a cell
  37. 37.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) always zero (c) their sum (d) more than either one
  39. 39.🧮 Resistors of 47 Ω, 68 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
  40. 40.Which of these is measured in ohms (Ω)? (a) energy used each second (b) voltage (c) power (d) how much a part resists

Answer key

  1. blows if current is high
  2. 3.75
  3. 5
  4. 5100
  5. False
  6. True
  7. 230
  8. blue-blue-orange
  9. False
  10. 50
  11. 0.25
  12. 16
  13. 850
  14. energy used each second
  15. V = I × R
  16. True
  17. 189
  18. 20
  19. 2.2
  20. 490
  21. saves electricity
  22. 4.5
  23. 157
  24. 3
  25. 900
  26. True
  27. 3
  28. R = V ÷ I
  29. to limit the current
  30. saves electricity
  31. anode (+)
  32. gets smaller
  33. 1
  34. 7.6
  35. True
  36. power
  37. 8.25
  38. less than either one
  39. 135
  40. how much a part resists

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