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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 93 · 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 100 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  2. 2.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  3. 3.🌈 A resistor has the colour bands green, red, yellow. What is its value in kilo-ohms (kΩ)? =
  4. 4.💡 What does LED stand for? (a) large electric dial (b) low energy device (c) light-emitting diode (d) light energy dial
  5. 5.What does a resistor do? (a) limits the current (b) lets current go one way (c) stores a little charge (d) makes a beeping sound
  6. 6.🧮 A 1.6 V battery is joined to 6 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  7. 7.📏 How many watts (W) is 1.2 kW?
  8. 8.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 5 % (c) 25 % (d) 50 %
  9. 9.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) stay the same (d) smaller
  10. 10.True or false: the ammeter is joined in series. (a) True (b) False
  11. 11.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  13. 13.⚡ A device works on 24 V and takes 0.25 A. What is its power (in watts)? =
  14. 14.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
  15. 15.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  16. 16.True or false: a motor turns a fan or wheels. (a) True (b) False
  17. 17.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
  18. 18.🧾 A 1000 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  19. 19.🧾 Which lamp gives the same light for the least power? (a) a filament bulb (b) a candle (c) an oil lamp (d) an LED lamp
  20. 20.⚡ A device works on 3 V and takes 0.25 A. What is its power (in watts)? =
  21. 21.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 300 Ω resistor? (a) orange-black-red (b) yellow-orange-brown (c) orange-black-brown (d) orange-black-black
  22. 22.True or false: a buzzer senses how hot it is. (a) False (b) True
  23. 23.📏 Which unit measures resistance? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
  24. 24.What does an LED do? (a) makes a beeping sound (b) makes things spin (c) turns a fan or wheels (d) glows using little power
  25. 25.True or false: resistance is measured in watts (W). (a) False (b) True
  26. 26.🧾 A 250 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  27. 27.🌈 A resistor has the colour bands white, grey, brown. What is its value (in ohms)?
  28. 28.True or false: energy used each second is measured in watts (W). (a) False (b) True
  29. 29.True or false: a thermistor beeps for an alarm. (a) True (b) False
  30. 30.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.True or false: to switch off empty rooms saves electricity. (a) False (b) True
  32. 32.True or false: the flow of charge is measured in amperes (A). (a) True (b) False
  33. 33.🧮 A 33 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)?
  34. 34.📏 In the water-pipe picture of a circuit, current is like … (a) the flow of water (b) the water pressure (c) a narrow pipe (d) the pipe colour
  35. 35.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 watt (c) 1 kilowatt-hour (kWh) (d) 1 volt
  36. 36.🔺 A current of 10 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.🌈 In the resistor colour code, which number does brown stand for?
  39. 39.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.💡 An LED is joined to a 12 V battery with no 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

Answer key

  1. 150
  2. True
  3. 520
  4. light-emitting diode
  5. limits the current
  6. 0.1
  7. 1200
  8. 5 %
  9. bigger
  10. True
  11. 1.2
  12. cathode (−)
  13. 6
  14. ammeter
  15. 5
  16. True
  17. 10
  18. 6
  19. an LED lamp
  20. 0.75
  21. orange-black-brown
  22. False
  23. ohm (Ω)
  24. glows using little power
  25. False
  26. 0.5
  27. 980
  28. True
  29. False
  30. 5
  31. True
  32. True
  33. 38
  34. the flow of water
  35. 1 kilowatt-hour (kWh)
  36. 300
  37. 1.5
  38. 1
  39. 6
  40. may burn out

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