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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 75 · 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.True or false: a diode lets current go one way. (a) False (b) True
  2. 2.🌈 A resistor has the colour bands blue, grey, brown. What is its value (in ohms)?
  3. 3.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  4. 4.True or false: a buzzer makes a beeping sound. (a) True (b) False
  5. 5.True or false: a capacitor smooths a wobbly supply. (a) False (b) True
  6. 6.📏 Voltmeter or ammeter: which one measures current? (a) ammeter (b) voltmeter
  7. 7.🌈 A resistor has the colour bands yellow, red, orange. What is its value in kilo-ohms (kΩ)? =
  8. 8.True or false: the push of a cell is measured in volts (V). (a) True (b) False
  9. 9.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
  10. 10.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
  11. 11.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.True or false: a transistor beeps for an alarm. (a) False (b) True
  13. 13.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 39 Ω resistor? (a) yellow-white-black (b) white-orange-black (c) orange-white-brown (d) orange-white-black
  14. 14.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 80 Ω resistor? (a) white-grey-black (b) grey-black-brown (c) white-black-black (d) grey-black-black
  15. 15.True or false: the ammeter measures voltage. (a) False (b) True
  16. 16.🔺 In the V-I-R triangle, how do we find I? (a) I = V + R (b) I = V ÷ R (c) I = R ÷ V (d) I = V × R
  17. 17.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
  18. 18.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = I ÷ V (d) P = V ÷ I
  19. 19.True or false: a resistor limits the current. (a) True (b) False
  20. 20.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to store charge (c) to make it brighter (d) to limit the current
  21. 21.📏 Which unit measures how much a part resists? (a) watt (W) (b) ohm (Ω) (c) volt (V) (d) ampere (A)
  22. 22.⚡ A device works on 3 V and takes 0.5 A. What is its power (in watts)? =
  23. 23.🌈 In the resistor colour code, which number does red stand for?
  24. 24.True or false: an LDR glows using little power. (a) False (b) True
  25. 25.📏 How many milliamperes (mA) is 1.56 A?
  26. 26.⚡ A device works on 24 V and takes 0.1 A. What is its power (in watts)? =
  27. 27.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 50000 Ω resistor? (a) green-black-red (b) blue-green-orange (c) green-black-orange (d) green-black-yellow
  28. 28.⚡ A device works on 12 V and takes 1 A. What is its power (in watts)? =
  29. 29.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 95000 Ω resistor? (a) white-green-orange (b) green-white-orange (c) white-green-yellow (d) white-green-red
  30. 30.Which of these is measured in ohms (Ω)? (a) the flow of charge (b) how much a part resists (c) power (d) the push of a cell
  31. 31.🔺 A 4.4 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  32. 32.🧾 One “unit” on an electricity bill is … (a) 1 watt (b) 1 ampere (c) 1 volt (d) 1 kilowatt-hour (kWh)
  33. 33.Which of these saves electricity? (a) leave the TV on standby (b) use old filament bulbs (c) use daylight to read (d) leave fridge door open
  34. 34.What does a potentiometer do? (a) is a resistance knob (b) has coloured bands (c) senses how hot it is (d) glows using little power
  35. 35.What does a thermistor do? (a) smooths a wobbly supply (b) senses how hot it is (c) makes a beeping sound (d) senses how bright it is
  36. 36.True or false: an LDR stores a little charge. (a) True (b) False
  37. 37.⚡ A 9 W device works on 3 V. What current does it take (in amperes)? =
  38. 38.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  39. 39.📏 How many milliamperes (mA) make 1 ampere? (a) 10 (b) 1000 (c) 60 (d) 100
  40. 40.🧩 A capacitor in a circuit can … (a) measure heat (b) spin a wheel (c) store charge briefly (d) make light

Answer key

  1. True
  2. 680
  3. cathode (−)
  4. True
  5. True
  6. ammeter
  7. 42
  8. True
  9. saves electricity
  10. 0.2
  11. 6
  12. False
  13. orange-white-black
  14. grey-black-black
  15. False
  16. I = V ÷ R
  17. True
  18. P = V × I
  19. True
  20. to limit the current
  21. ohm (Ω)
  22. 1.5
  23. 2
  24. False
  25. 1560
  26. 2.4
  27. green-black-orange
  28. 12
  29. white-green-orange
  30. how much a part resists
  31. 20
  32. 1 kilowatt-hour (kWh)
  33. use daylight to read
  34. is a resistance knob
  35. senses how hot it is
  36. False
  37. 3
  38. 115
  39. 1000
  40. store charge briefly

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