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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 503 · 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 330 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  2. 2.⚡ A 2.4 W device works on 24 V. What current does it take (in amperes)? =
  3. 3.🔺 A current of 0.1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  5. 5.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
  6. 6.True or false: a capacitor senses how hot it is. (a) True (b) False
  7. 7.🌈 A resistor has the colour bands violet, brown, orange. What is its value (in ohms)?
  8. 8.True or false: on an LED, the shorter leg is the cathode (−). (a) True (b) False
  9. 9.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  11. 11.🌈 Which band is read first on a resistor? (a) the widest gap (b) the gold band (c) any band (d) the one nearest an end
  12. 12.📏 Which unit measures the push of a cell? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
  13. 13.🧾 A 2000 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  14. 14.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it lights brighter (d) it does not light
  15. 15.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 92 Ω resistor? (a) white-red-brown (b) red-white-black (c) brown-red-black (d) white-red-black
  16. 16.🧩 Which component is a resistance knob? (a) LDR (b) LED (c) thermistor (d) potentiometer
  17. 17.🔺 A 2.5 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  18. 18.🧩 Which component senses how bright it is? (a) resistor (b) LDR (c) LED (d) buzzer
  19. 19.📏 How many milliamperes (mA) is 1.49 A?
  20. 20.🔺 A current of 2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.Which of these is measured in amperes (A)? (a) power (b) how much a part resists (c) resistance (d) the flow of charge
  22. 22.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  23. 23.🧮 A 4.5 V battery is joined to 6 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
  24. 24.🔺 A current of 50 mA flows when 16.5 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.True or false: voltage is measured in volts (V). (a) False (b) True
  26. 26.💡 An LED is joined to a 9 V battery through a 220 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
  27. 27.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
  29. 29.💡 Does it save or waste electricity to use LED lamps? (a) saves electricity (b) wastes electricity
  30. 30.True or false: an LED glows using little power. (a) True (b) False
  31. 31.🔺 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
  32. 32.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
  33. 33.🔺 A current of 0.25 A flows when 1.25 V is joined across a resistor. What is its resistance (in ohms)?
  34. 34.⚡ A 3 W device works on 3 V. What current does it take (in amperes)? =
  35. 35.🧾 One “unit” on an electricity bill is … (a) 1 ampere (b) 1 kilowatt-hour (kWh) (c) 1 volt (d) 1 watt
  36. 36.🔺 A 5 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  37. 37.⚡ A device works on 24 V and takes 1 A. What is its power (in watts)? =
  38. 38.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
  39. 39.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
  40. 40.🔺 A current of 0.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 340
  2. 0.1
  3. 0.2
  4. anode (+)
  5. saves electricity
  6. False
  7. 71000
  8. True
  9. 6
  10. 165
  11. the one nearest an end
  12. volt (V)
  13. 16
  14. it does not light
  15. white-red-black
  16. potentiometer
  17. 0.25
  18. LDR
  19. 1490
  20. 4
  21. the flow of charge
  22. 5
  23. 0.5
  24. 330
  25. True
  26. does not light
  27. 6
  28. ammeter
  29. saves electricity
  30. True
  31. R = V ÷ I
  32. 378
  33. 5
  34. 1
  35. 1 kilowatt-hour (kWh)
  36. 25
  37. 24
  38. P = V × I
  39. 5 %
  40. 6

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