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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 236 · 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 current of 0.1 A flows when 0.3 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.🌈 In the resistor colour code, which number does green stand for?
  3. 3.⚡ A device works on 24 V and takes 3 A. What is its power (in watts)? =
  4. 4.What does a resistor do? (a) has coloured bands (b) lets current go one way (c) smooths a wobbly supply (d) is a resistance knob
  5. 5.🧮 A 1 V battery is joined to 6 Ω and 4 Ω resistors in series. What current flows (in amperes)? =
  6. 6.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  7. 7.📏 How many milliamperes (mA) is 2.75 A?
  8. 8.🔺 A current of 1.5 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.💡 What does LED stand for? (a) light-emitting diode (b) light energy dial (c) large electric dial (d) low energy device
  10. 10.🧮 Resistors of 220 Ω, 22 Ω, 47 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  11. 11.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 25 % (c) 5 % (d) 50 %
  12. 12.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 720 Ω resistor? (a) red-violet-brown (b) violet-red-red (c) violet-red-black (d) violet-red-brown
  13. 13.📏 Which unit measures voltage? (a) volt (V) (b) ampere (A) (c) ohm (Ω) (d) watt (W)
  14. 14.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  15. 15.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) smaller (d) stay the same
  16. 16.🌈 In the resistor colour code, which number does blue stand for?
  17. 17.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) stays the same (d) gets bigger
  18. 18.💡 Does it save or waste electricity to use daylight to read? (a) saves electricity (b) wastes electricity
  19. 19.🔺 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
  20. 20.What does an LDR do? (a) senses how bright it is (b) beeps for an alarm (c) is a resistance knob (d) smooths a wobbly supply
  21. 21.🌈 A resistor has the colour bands red, white, red. What is its value (in ohms)?
  22. 22.⚡ A device works on 24 V and takes 0.25 A. What is its power (in watts)? =
  23. 23.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
  24. 24.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  25. 25.🌈 A resistor has the colour bands red, black, brown. What is its value (in ohms)?
  26. 26.True or false: the voltmeter is joined in series. (a) True (b) False
  27. 27.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  28. 28.True or false: a resistor has coloured bands. (a) True (b) False
  29. 29.Which of these is measured in ohms (Ω)? (a) power (b) current (c) resistance (d) the flow of charge
  30. 30.🌈 A resistor has the colour bands red, orange, orange. What is its value in kilo-ohms (kΩ)? =
  31. 31.What does a diode do? (a) stores a little charge (b) lets current go one way (c) limits the current (d) senses how hot it is
  32. 32.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a candle (c) an oil lamp (d) a filament bulb
  33. 33.🧮 Resistors of 470 Ω, 47 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  34. 34.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  35. 35.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
  36. 36.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
  37. 37.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  38. 38.📏 How many kilo-ohms (kΩ) is 7000 Ω? =
  39. 39.📏 How many ohms (Ω) is 9.1 kΩ?
  40. 40.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =

Answer key

  1. 3
  2. 5
  3. 72
  4. has coloured bands
  5. 0.1
  6. anode (+)
  7. 2750
  8. 8
  9. light-emitting diode
  10. 619
  11. 5 %
  12. violet-red-brown
  13. volt (V)
  14. 40
  15. bigger
  16. 6
  17. gets smaller
  18. saves electricity
  19. V = I × R
  20. senses how bright it is
  21. 2900
  22. 6
  23. 400
  24. cathode (−)
  25. 200
  26. False
  27. 10
  28. True
  29. resistance
  30. 23
  31. lets current go one way
  32. an LED lamp
  33. 567
  34. 50
  35. store charge briefly
  36. P = V × I
  37. 100
  38. 7
  39. 9100
  40. 6

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