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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 325 · 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.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  2. 2.True or false: on an LED, the longer leg is the anode (+). (a) True (b) False
  3. 3.🔍 Which is the odd one out? (a) run fans in empty rooms (b) close the fridge quickly (c) use daylight to read (d) use LED lamps
  4. 4.⚡ A device works on 24 V and takes 0.2 A. What is its power (in watts)? =
  5. 5.💡 An LED is joined to a 9 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) may burn out (c) does not light
  6. 6.🔺 A 1.6 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  7. 7.🌈 In the resistor colour code, which number does blue stand for?
  8. 8.🔺 A 4.5 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  9. 9.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) use daylight to read (c) leave fridge door open (d) switch off empty rooms
  10. 10.What does a capacitor do? (a) stores a little charge (b) makes a beeping sound (c) is a resistance knob (d) senses how bright it is
  11. 11.🔺 A 5 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  12. 12.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = V ÷ R (d) I = R ÷ V
  13. 13.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = I ÷ V (d) P = V ÷ I
  14. 14.🔺 A current of 1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  15. 15.True or false: a motor makes things spin. (a) True (b) False
  16. 16.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 watt (d) 1 ampere
  17. 17.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  18. 18.🔺 A current of 0.2 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🧩 Which component has coloured bands? (a) capacitor (b) motor (c) resistor (d) fuse
  20. 20.🧩 Which part changes electrical energy into movement? (a) a motor (b) a resistor (c) an LED (d) a fuse
  21. 21.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  22. 22.🔺 A current of 3 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 4400 Ω resistor? (a) yellow-yellow-orange (b) yellow-yellow-red (c) yellow-yellow-brown (d) yellow-green-red
  24. 24.⚡ A 2.4 W device works on 12 V. What current does it take (in amperes)? =
  25. 25.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  26. 26.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) their sum (d) less than either one
  27. 27.Which of these saves electricity? (a) use old filament bulbs (b) leave fridge door open (c) use LED lamps (d) iron one shirt at a time
  28. 28.🌈 In the resistor colour code, which number does violet stand for?
  29. 29.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  31. 31.🔺 A 1 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  32. 32.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  33. 33.🧾 A 40 W filament bulb is swapped for a 6 W LED lamp that gives about the same light. Both would run for 8 hours. How many watt-hours (Wh) are saved?
  34. 34.🔺 A current of 2 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.📏 How many ohms (Ω) is 8.1 kΩ?
  36. 36.🧩 Which component limits the current? (a) resistor (b) fuse (c) potentiometer (d) buzzer
  37. 37.⚡ A device works on 5 V and takes 3 A. What is its power (in watts)? =
  38. 38.🌈 A resistor has the colour bands brown, blue, brown. What is its value (in ohms)?
  39. 39.🔺 A current of 0.5 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  40. 40.📏 In the water-pipe picture of a circuit, resistance is like … (a) a bigger tank (b) the water pressure (c) the flow of water (d) a narrow pipe

Answer key

  1. 10
  2. True
  3. run fans in empty rooms
  4. 4.8
  5. does not light
  6. 0.2
  7. 6
  8. 1.5
  9. leave fridge door open
  10. stores a little charge
  11. 0.25
  12. I = V ÷ R
  13. P = V × I
  14. 2
  15. True
  16. 1 kilowatt-hour (kWh)
  17. voltmeter
  18. 2
  19. resistor
  20. a motor
  21. 40
  22. 30
  23. yellow-yellow-red
  24. 0.2
  25. voltmeter
  26. less than either one
  27. use LED lamps
  28. 7
  29. 2
  30. anode (+)
  31. 10
  32. 6
  33. 272
  34. 8
  35. 8100
  36. resistor
  37. 15
  38. 160
  39. 5
  40. a narrow pipe

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