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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 996 · 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.⚡ Power tells us … (a) the length of a wire (b) the size of a cell (c) the colour of light (d) energy used each second
  2. 2.💡 An LED is joined to a 9 V battery through a 1000 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) lights up (c) does not light
  3. 3.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V × I (d) R = V + I
  4. 4.🧮 A 20 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  5. 5.🔺 A current of 1 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 23 Ω resistor? (a) red-orange-black (b) orange-orange-black (c) orange-red-black (d) red-orange-brown
  7. 7.🔺 A current of 40 mA flows when 13.2 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🧮 Resistors of 68 Ω, 68 Ω, 150 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  9. 9.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  10. 10.🧮 Resistors of 470 Ω, 150 Ω, 220 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  11. 11.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  12. 12.🔺 A current of 1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.🌈 A resistor has the colour bands yellow, violet, yellow. What is its value in kilo-ohms (kΩ)? =
  15. 15.True or false: voltage is measured in watts (W). (a) True (b) False
  16. 16.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.True or false: an LED glows using little power. (a) True (b) False
  18. 18.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🔺 A current of 40 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.🔺 A current of 0.2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.🌈 Which band is read first on a resistor? (a) the widest gap (b) the one nearest an end (c) the gold band (d) any band
  22. 22.🔺 A current of 3 A flows when 60 V is joined across a resistor. What is its resistance (in ohms)?
  23. 23.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 5 % (d) 50 %
  24. 24.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
  25. 25.💡 Does it save or waste electricity to unplug idle chargers? (a) wastes electricity (b) saves electricity
  26. 26.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.🧾 A 1500 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
  28. 28.True or false: power is measured in volts (V). (a) True (b) False
  29. 29.🔺 A current of 0.2 A flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🌈 In the resistor colour code, which number does black stand for?
  31. 31.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  32. 32.⚡ A device works on 9 V and takes 0.2 A. What is its power (in watts)? =
  33. 33.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  34. 34.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to store charge (c) to change its colour (d) to make it brighter
  35. 35.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
  36. 36.🔺 A 3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  37. 37.🌈 A resistor has the colour bands white, red, yellow. What is its value in kilo-ohms (kΩ)? =
  38. 38.🔍 Which is the odd one out? (a) use LED lamps (b) leave fridge door open (c) set the AC to 24 °C (d) close the fridge quickly
  39. 39.What does a transistor do? (a) boosts a small signal (b) makes a beeping sound (c) senses how hot it is (d) glows using little power
  40. 40.True or false: to use old filament bulbs wastes electricity. (a) False (b) True

Answer key

  1. energy used each second
  2. does not light
  3. R = V ÷ I
  4. 520
  5. 4
  6. red-orange-black
  7. 330
  8. 319
  9. cathode (−)
  10. 1170
  11. ammeter
  12. 6
  13. 15
  14. 470
  15. False
  16. 0.4
  17. True
  18. 5
  19. 12
  20. 1.6
  21. the one nearest an end
  22. 20
  23. 5 %
  24. voltmeter
  25. saves electricity
  26. 8.8
  27. 15
  28. False
  29. 12
  30. 0
  31. anode (+)
  32. 1.8
  33. anode (+)
  34. to limit the current
  35. False
  36. 1
  37. 920
  38. leave fridge door open
  39. boosts a small signal
  40. True

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