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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 823 · 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.What does a diode do? (a) limits the current (b) blows if current is high (c) senses how hot it is (d) lets current go one way
  2. 2.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  3. 3.🌈 A resistor has the colour bands brown, grey, yellow. What is its value in kilo-ohms (kΩ)? =
  4. 4.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  5. 5.📏 Which unit measures voltage? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
  6. 6.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) a motor (d) an LED
  7. 7.📏 In the water-pipe picture of a circuit, current is like … (a) a narrow pipe (b) the flow of water (c) the water pressure (d) the pipe colour
  8. 8.🔺 A current of 10 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) run fans in empty rooms (c) use old filament bulbs (d) iron one shirt at a time
  10. 10.📏 How many kilowatts (kW) is 3750 W? =
  11. 11.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.⚡ An 18 W device works on 6 V. What current does it take (in amperes)? =
  13. 13.🧩 Which component has coloured bands? (a) motor (b) resistor (c) fuse (d) diode
  14. 14.🔺 A current of 10 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🧩 Which component smooths a wobbly supply? (a) capacitor (b) motor (c) thermistor (d) diode
  16. 16.True or false: the voltmeter is joined across a part. (a) True (b) False
  17. 17.🧮 Three equal 60 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  18. 18.🌈 In the resistor colour code, which number does violet stand for?
  19. 19.💡 An LED is joined to a 9 V battery with no 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
  20. 20.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) less than either one (c) their sum (d) always zero
  21. 21.💡 Does it save or waste electricity to iron one shirt at a time? (a) wastes electricity (b) saves electricity
  22. 22.🔺 A current of 25 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.📏 How many amperes (A) is 2470 mA? =
  24. 24.⚡ A device works on 1.5 V and takes 0.1 A. What is its power (in watts)? =
  25. 25.True or false: to leave the TV on standby wastes electricity. (a) False (b) True
  26. 26.🔺 A current of 0.1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  27. 27.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  28. 28.⚡ A 36 W device works on 12 V. What current does it take (in amperes)? =
  29. 29.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 49000 Ω resistor? (a) yellow-white-red (b) white-yellow-orange (c) yellow-white-yellow (d) yellow-white-orange
  30. 30.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  31. 31.📏 How many kilowatts (kW) is 2800 W? =
  32. 32.⚡ A 2.25 W device works on 9 V. What current does it take (in amperes)? =
  33. 33.🌈 A resistor has the colour bands yellow, yellow, orange. What is its value in kilo-ohms (kΩ)? =
  34. 34.🌈 In the resistor colour code, which number does green stand for?
  35. 35.🔺 A 12.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  36. 36.True or false: a capacitor stores a little charge. (a) True (b) False
  37. 37.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) stays the same (c) gets bigger (d) becomes zero
  38. 38.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.🧾 A family uses 120 units of electricity in a month and each unit costs ₹9. What is the bill (in ₹)?
  40. 40.Which of these wastes electricity? (a) leave fridge door open (b) use LED lamps (c) set the AC to 24 °C (d) close the fridge quickly

Answer key

  1. lets current go one way
  2. 920
  3. 180
  4. voltmeter
  5. volt (V)
  6. a motor
  7. the flow of water
  8. 3
  9. set the AC to 24 °C
  10. 3.75
  11. 25
  12. 3
  13. resistor
  14. 2.2
  15. capacitor
  16. True
  17. 20
  18. 7
  19. may burn out
  20. less than either one
  21. wastes electricity
  22. 7.5
  23. 2.47
  24. 0.15
  25. True
  26. 1.5
  27. cathode (−)
  28. 3
  29. yellow-white-orange
  30. 80
  31. 2.8
  32. 0.25
  33. 44
  34. 5
  35. 50
  36. True
  37. gets smaller
  38. 0.6
  39. 1080
  40. leave fridge door open

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