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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 745 · 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.💡 An LED is joined to a 6 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  2. 2.What does a capacitor do? (a) senses how hot it is (b) limits the current (c) lets current go one way (d) smooths a wobbly supply
  3. 3.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
  4. 4.🌈 A resistor has the colour bands yellow, green, red. What is its value in kilo-ohms (kΩ)? =
  5. 5.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🧮 Resistors of 22 Ω, 150 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  7. 7.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it changes colour (d) it lights brighter
  8. 8.Which of these saves electricity? (a) iron one shirt at a time (b) switch off empty rooms (c) use old filament bulbs (d) leave fridge door open
  9. 9.True or false: a transistor glows using little power. (a) True (b) False
  10. 10.⚡ A device works on 1.5 V and takes 2 A. What is its power (in watts)? =
  11. 11.🔺 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
  12. 12.🔺 A 37.5 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  13. 13.⚡ 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
  14. 14.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  15. 15.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 470 Ω resistor? (a) yellow-violet-brown (b) violet-yellow-brown (c) yellow-violet-red (d) yellow-violet-black
  16. 16.💡 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)?
  17. 17.🔺 A current of 0.2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.🧮 A 33 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  19. 19.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 25 % (d) 50 %
  21. 21.🔺 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
  22. 22.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) stay the same (c) smaller (d) bigger
  23. 23.🧮 A 22 Ω resistor is joined in series with two equal 200 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  24. 24.🌈 A resistor has the colour bands green, brown, black. What is its value (in ohms)?
  25. 25.🔺 A current of 3 A flows when 45 V is joined across a resistor. What is its resistance (in ohms)?
  26. 26.🧮 Resistors of 470 Ω, 150 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
  27. 27.📏 How many milliamperes (mA) is 1.61 A?
  28. 28.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light
  29. 29.True or false: a transistor boosts a small signal. (a) True (b) False
  30. 30.🔺 A current of 50 mA flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🌈 In the resistor colour code, which number does grey stand for?
  32. 32.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 50000 Ω resistor? (a) green-black-yellow (b) green-black-red (c) blue-green-orange (d) green-black-orange
  33. 33.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) less than either one (d) always zero
  35. 35.🔺 A current of 50 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🧾 A 1500 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  37. 37.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V + I (d) P = V ÷ I
  38. 38.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 36 Ω resistor? (a) yellow-blue-black (b) orange-blue-black (c) orange-blue-brown (d) blue-orange-black
  39. 39.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
  40. 40.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?

Answer key

  1. lights up
  2. smooths a wobbly supply
  3. 85
  4. 4.5
  5. 5
  6. 392
  7. it does not light
  8. switch off empty rooms
  9. False
  10. 3
  11. R = V ÷ I
  12. 2.5
  13. energy used each second
  14. 50
  15. yellow-violet-brown
  16. 5
  17. 3
  18. 198
  19. 25
  20. 5 %
  21. gets smaller
  22. bigger
  23. 122
  24. 51
  25. 15
  26. 688
  27. 1610
  28. store charge briefly
  29. True
  30. 500
  31. 8
  32. green-black-orange
  33. 15
  34. less than either one
  35. 6
  36. 3
  37. P = V × I
  38. orange-blue-black
  39. 0.2
  40. 100

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