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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 865 · 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: to set the AC to 24 °C saves electricity. (a) False (b) True
  2. 2.🌈 A resistor has the colour bands violet, grey, brown. What is its value (in ohms)?
  3. 3.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
  4. 4.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  5. 5.🔺 A current of 3 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.📏 How many milliamperes (mA) is 1.7 A?
  7. 7.🧾 A family uses 40 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
  8. 8.🧩 Which component makes things spin? (a) transistor (b) fuse (c) buzzer (d) motor
  9. 9.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 4900 Ω resistor? (a) yellow-white-brown (b) yellow-white-red (c) yellow-white-orange (d) white-yellow-red
  10. 10.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) bigger (d) zero
  11. 11.⚡ A 0.3 W device works on 3 V. What current does it take (in amperes)? =
  12. 12.🔺 A current of 0.1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  14. 14.🔺 A current of 0.2 A flows when 0.8 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  16. 16.Which of these saves electricity? (a) set the AC to 24 °C (b) leave fridge door open (c) run fans in empty rooms (d) leave the TV on standby
  17. 17.🌈 A resistor has the colour bands white, green, red. What is its value in kilo-ohms (kΩ)? =
  18. 18.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) does not light (b) may burn out (c) lights up
  19. 19.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  20. 20.🔺 A current of 50 mA flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.⚡ A 0.9 W device works on 9 V. What current does it take (in amperes)? =
  22. 22.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
  23. 23.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a filament bulb (c) a candle (d) an LED lamp
  24. 24.True or false: a motor turns a fan or wheels. (a) True (b) False
  25. 25.🔍 Which is the odd one out? (a) close the fridge quickly (b) use daylight to read (c) leave the TV on standby (d) set the AC to 24 °C
  26. 26.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a motor (c) a resistor (d) an LED
  27. 27.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  28. 28.🔺 A 9.4 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.🌈 A resistor has the colour bands orange, brown, red. What is its value in kilo-ohms (kΩ)? =
  30. 30.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  31. 31.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
  32. 32.🔺 A 12 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  33. 33.⚡ A device works on 24 V and takes 2 A. What is its power (in watts)? =
  34. 34.🔺 A current of 0.1 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.True or false: the push of a cell is measured in amperes (A). (a) False (b) True
  36. 36.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  37. 37.Which of these wastes electricity? (a) set the AC to 24 °C (b) use daylight to read (c) use old filament bulbs (d) close the fridge quickly
  38. 38.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  39. 39.🌈 In the resistor colour code, which number does green stand for?
  40. 40.⚡ A 4.5 W device works on 1.5 V. What current does it take (in amperes)? =

Answer key

  1. True
  2. 780
  3. R = V ÷ I
  4. 165
  5. 4
  6. 1700
  7. 160
  8. motor
  9. yellow-white-red
  10. bigger
  11. 0.1
  12. 0.4
  13. 5
  14. 4
  15. ammeter
  16. set the AC to 24 °C
  17. 9.5
  18. does not light
  19. anode (+)
  20. 100
  21. 0.1
  22. 5 %
  23. an LED lamp
  24. True
  25. leave the TV on standby
  26. a motor
  27. 600
  28. 20
  29. 3.1
  30. 920
  31. True
  32. 1.5
  33. 48
  34. 0.8
  35. False
  36. anode (+)
  37. use old filament bulbs
  38. 25
  39. 5
  40. 3

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