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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 69 · 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.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
  2. 2.📏 In the water-pipe picture of a circuit, voltage is like … (a) the pipe colour (b) the water tank lid (c) the tap handle (d) the water pressure
  3. 3.📏 Which unit measures current? (a) ampere (A) (b) volt (V) (c) watt (W) (d) ohm (Ω)
  4. 4.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.🧮 A 220 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)?
  6. 6.Which of these is measured in watts (W)? (a) the flow of charge (b) power (c) current (d) resistance
  7. 7.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
  8. 8.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  9. 9.🌈 A resistor has the colour bands red, red, red. What is its value in kilo-ohms (kΩ)? =
  10. 10.🧮 Resistors of 100 Ω, 33 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  11. 11.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  12. 12.🧾 A 100 W filament bulb is swapped for a 15 W LED lamp that gives about the same light. Both would run for 4 hours. How many watt-hours (Wh) are saved?
  13. 13.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  14. 14.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🌈 In the resistor colour code, which number does orange stand for?
  16. 16.🔺 A current of 0.2 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🔺 A current of 0.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  18. 18.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
  19. 19.🌈 A resistor has the colour bands orange, red, red. What is its value (in ohms)?
  20. 20.🔺 A current of 40 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  22. 22.True or false: an LDR senses how bright it is. (a) False (b) True
  23. 23.⚡ A 0.75 W device works on 3 V. What current does it take (in amperes)? =
  24. 24.Which of these saves electricity? (a) run fans in empty rooms (b) set the AC to 24 °C (c) iron one shirt at a time (d) leave fridge door open
  25. 25.🧮 A 5.5 V battery is joined to 5 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  26. 26.⚡ A device works on 9 V and takes 1.5 A. What is its power (in watts)? =
  27. 27.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) gets smaller (c) stays the same (d) becomes zero
  28. 28.🔺 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
  29. 29.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  30. 30.🔺 A 16.5 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  31. 31.🔺 A current of 0.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🔺 A 5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  33. 33.📏 How many milliamperes (mA) is 1.24 A?
  34. 34.🌈 A resistor has the colour bands brown, green, black. What is its value (in ohms)?
  35. 35.📏 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
  36. 36.🧩 Which component limits the current? (a) resistor (b) fuse (c) LDR (d) motor
  37. 37.What does a thermistor do? (a) senses how hot it is (b) blows if current is high (c) makes things spin (d) has coloured bands
  38. 38.💡 Does it save or waste electricity to leave fridge door open? (a) wastes electricity (b) saves electricity
  39. 39.📏 How many milliamperes (mA) make 1 ampere? (a) 100 (b) 60 (c) 1000 (d) 10
  40. 40.What does a fuse do? (a) blows if current is high (b) makes things spin (c) smooths a wobbly supply (d) boosts a small signal

Answer key

  1. wastes electricity
  2. the water pressure
  3. ampere (A)
  4. 0.6
  5. 230
  6. power
  7. 12
  8. 2300
  9. 2.2
  10. 603
  11. 115
  12. 340
  13. 10
  14. 3
  15. 3
  16. 1
  17. 15
  18. saves electricity
  19. 3200
  20. 20
  21. False
  22. True
  23. 0.25
  24. set the AC to 24 °C
  25. 0.5
  26. 13.5
  27. gets smaller
  28. I = V ÷ R
  29. anode (+)
  30. 50
  31. 1.5
  32. 2.5
  33. 1240
  34. 15
  35. the flow of water
  36. resistor
  37. senses how hot it is
  38. wastes electricity
  39. 1000
  40. blows if current is high

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