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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 809 · 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.True or false: a motor turns a fan or wheels. (a) False (b) True
  2. 2.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the colour of light (d) the size of a cell
  3. 3.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  4. 4.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  5. 5.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  6. 6.True or false: a transistor boosts a small signal. (a) True (b) False
  7. 7.🔺 A current of 2.5 A flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.⚡ A 7.5 W device works on 5 V. What current does it take (in amperes)? =
  9. 9.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) their sum (d) always zero
  11. 11.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 4 V supply. What current flows (in mA)?
  12. 12.🔺 A current of 0.1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the gold band (d) the widest gap
  16. 16.🔺 A current of 0.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🔺 A current of 10 mA flows when 3.3 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  19. 19.True or false: to use LED lamps saves electricity. (a) True (b) False
  20. 20.🔺 A current of 50 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
  22. 22.🌈 A resistor has the colour bands orange, orange, yellow. What is its value in kilo-ohms (kΩ)? =
  23. 23.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  24. 24.📏 Which unit measures resistance? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
  25. 25.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) store charge briefly (d) spin a wheel
  26. 26.🧮 A 20 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)?
  27. 27.True or false: the flow of charge is measured in watts (W). (a) True (b) False
  28. 28.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  30. 30.🧮 A 10 Ω resistor is joined in series with two equal 10 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  31. 31.⚡ A device works on 24 V and takes 1 A. What is its power (in watts)? =
  32. 32.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  33. 33.🧾 A family uses 40 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
  34. 34.🧮 A 2.25 V battery is joined to 5 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  35. 35.🔺 A current of 0.25 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🌈 A resistor has the colour bands red, green, orange. What is its value in kilo-ohms (kΩ)? =
  37. 37.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  38. 38.🌈 A resistor has the colour bands green, violet, red. What is its value in kilo-ohms (kΩ)? =
  39. 39.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.🔺 A current of 50 mA flows when 16.5 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

  1. True
  2. energy used each second
  3. 115
  4. 5
  5. cathode (−)
  6. True
  7. 10
  8. 1.5
  9. 9
  10. less than either one
  11. 20
  12. 1
  13. 6
  14. 0.5
  15. the one nearest an end
  16. 2
  17. 330
  18. 400
  19. True
  20. 20
  21. gets smaller
  22. 330
  23. False
  24. ohm (Ω)
  25. store charge briefly
  26. 130
  27. False
  28. 2
  29. 510
  30. 15
  31. 24
  32. 20
  33. 320
  34. 0.25
  35. 2.5
  36. 25
  37. 345
  38. 5.7
  39. 120
  40. 330

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