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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 578 · 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.🧩 A capacitor in a circuit can … (a) make light (b) spin a wheel (c) measure heat (d) store charge briefly
  2. 2.🌈 A resistor has the colour bands brown, black, orange. What is its value in kilo-ohms (kΩ)? =
  3. 3.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🔺 An 8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  5. 5.True or false: a fuse blows if current is high. (a) False (b) True
  6. 6.📏 Which unit measures voltage? (a) volt (V) (b) ampere (A) (c) watt (W) (d) ohm (Ω)
  7. 7.⚡ Power tells us … (a) the size of a cell (b) energy used each second (c) the colour of light (d) the length of a wire
  8. 8.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
  10. 10.🔺 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
  11. 11.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  12. 12.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  13. 13.🔺 A current of 0.2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🧮 A 100 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)?
  15. 15.True or false: to use old filament bulbs saves electricity. (a) True (b) False
  16. 16.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.Which of these is measured in watts (W)? (a) the flow of charge (b) current (c) voltage (d) energy used each second
  18. 18.🔺 A 30 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  19. 19.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  20. 20.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  21. 21.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) smaller (c) stay the same (d) zero
  22. 22.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it does not light (d) it changes colour
  23. 23.📏 How many watts (W) is 0.8 kW?
  24. 24.📏 Which unit measures current? (a) ohm (Ω) (b) volt (V) (c) watt (W) (d) ampere (A)
  25. 25.💡 An LED is joined to a 9 V battery through a 470 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  26. 26.🧾 A 1500 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  27. 27.🌈 In the resistor colour code, which number does violet stand for?
  28. 28.💡 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)?
  29. 29.True or false: to set the AC to 24 °C wastes electricity. (a) True (b) False
  30. 30.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 0 % (d) 5 %
  31. 31.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  32. 32.🧮 Resistors of 20 Ω, 220 Ω, 33 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  33. 33.Which of these saves electricity? (a) run fans in empty rooms (b) use old filament bulbs (c) leave fridge door open (d) set the AC to 24 °C
  34. 34.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I ÷ R (c) V = R ÷ I (d) V = I + R
  35. 35.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  36. 36.🔺 A current of 0.2 A flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.⚡ A 9 W device works on 9 V. What current does it take (in amperes)? =
  38. 38.🌈 In the resistor colour code, which number does grey stand for?
  39. 39.🧾 A family uses 90 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
  40. 40.⚡ A device works on 5 V and takes 1 A. What is its power (in watts)? =

Answer key

  1. store charge briefly
  2. 10
  3. 12.5
  4. 2
  5. True
  6. volt (V)
  7. energy used each second
  8. 1.2
  9. P = V × I
  10. I = V ÷ R
  11. True
  12. 5
  13. 0.8
  14. 200
  15. False
  16. 1.2
  17. energy used each second
  18. 1.5
  19. 10
  20. cathode (−)
  21. bigger
  22. it does not light
  23. 800
  24. ampere (A)
  25. lights up
  26. 9
  27. 7
  28. 5
  29. False
  30. 5 %
  31. 110
  32. 743
  33. set the AC to 24 °C
  34. V = I × R
  35. 345
  36. 12
  37. 1
  38. 8
  39. 720
  40. 5

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