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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 778 · 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 9 V battery is joined to 4 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
  2. 2.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) becomes zero (d) gets smaller
  3. 3.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) any band (c) the widest gap (d) the gold band
  4. 4.🧮 A 100 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  5. 5.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  6. 6.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  7. 7.🔺 A 3 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  8. 8.🔍 Which is the odd one out? (a) iron one shirt at a time (b) leave the TV on standby (c) run fans in empty rooms (d) use daylight to read
  9. 9.🧾 A 100 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
  10. 10.⚡ A device works on 6 V and takes 0.5 A. What is its power (in watts)? =
  11. 11.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 ampere (c) 1 kilowatt-hour (kWh) (d) 1 watt
  12. 12.🔺 A current of 40 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.Which of these is measured in amperes (A)? (a) the push of a cell (b) how much a part resists (c) current (d) energy used each second
  14. 14.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 100 (c) 60 (d) 1000
  15. 15.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
  16. 16.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
  17. 17.📏 Which unit measures resistance? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
  18. 18.🌈 A resistor has the colour bands red, yellow, black. What is its value (in ohms)?
  19. 19.💡 Does it save or waste electricity to set the AC to 24 °C? (a) saves electricity (b) wastes electricity
  20. 20.What does an LED do? (a) glows using little power (b) makes things spin (c) limits the current (d) senses how hot it is
  21. 21.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I ÷ R (c) V = I + R (d) V = R ÷ I
  22. 22.What does a potentiometer do? (a) stores a little charge (b) limits the current (c) is a resistance knob (d) has coloured bands
  23. 23.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) stay the same (d) smaller
  24. 24.True or false: the voltmeter is joined across a part. (a) False (b) True
  25. 25.True or false: the push of a cell is measured in volts (V). (a) True (b) False
  26. 26.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  27. 27.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  28. 28.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
  29. 29.True or false: a diode blows if current is high. (a) False (b) True
  30. 30.🧮 A 470 Ω resistor is joined in series with two equal 330 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  31. 31.🧩 Which component stores a little charge? (a) capacitor (b) fuse (c) LDR (d) potentiometer
  32. 32.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to limit the current (c) to store charge (d) to change its colour
  33. 33.📏 In the water-pipe picture of a circuit, current is like … (a) the water pressure (b) the pipe colour (c) a narrow pipe (d) the flow of water
  34. 34.🔺 A current of 40 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.Which of these is measured in watts (W)? (a) energy used each second (b) resistance (c) the push of a cell (d) current
  36. 36.True or false: power is measured in ohms (Ω). (a) True (b) False
  37. 37.Which of these wastes electricity? (a) set the AC to 24 °C (b) switch off empty rooms (c) unplug idle chargers (d) leave the TV on standby
  38. 38.Which of these saves electricity? (a) switch off empty rooms (b) run fans in empty rooms (c) iron one shirt at a time (d) leave the TV on standby
  39. 39.⚡ A 24 W device works on 24 V. What current does it take (in amperes)? =
  40. 40.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 1
  2. gets smaller
  3. the one nearest an end
  4. 210
  5. cathode (−)
  6. 500
  7. 0.25
  8. use daylight to read
  9. 1
  10. 3
  11. 1 kilowatt-hour (kWh)
  12. 4
  13. current
  14. 1000
  15. saves electricity
  16. P = V × I
  17. ohm (Ω)
  18. 24
  19. saves electricity
  20. glows using little power
  21. V = I × R
  22. is a resistance knob
  23. bigger
  24. True
  25. True
  26. 40
  27. 25
  28. False
  29. False
  30. 635
  31. capacitor
  32. to limit the current
  33. the flow of water
  34. 13.2
  35. energy used each second
  36. False
  37. leave the TV on standby
  38. switch off empty rooms
  39. 1
  40. 2.2

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