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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 929 · 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.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 70 Ω resistor? (a) violet-black-black (b) grey-violet-black (c) grey-black-black (d) violet-black-brown
  2. 2.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
  3. 3.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = R ÷ V (c) I = V + R (d) I = V × R
  4. 4.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  5. 5.🧮 A 330 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.🧮 A 470 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)?
  7. 7.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
  9. 9.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  11. 11.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 25 % (c) 5 % (d) 0 %
  12. 12.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V ÷ I (c) P = V + I (d) P = V × I
  13. 13.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the gold band (d) the widest gap
  14. 14.📏 How many ohms (Ω) is 7.4 kΩ?
  15. 15.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V ÷ I (d) R = V × I
  16. 16.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  17. 17.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  18. 18.⚡ A 2.4 W device works on 24 V. What current does it take (in amperes)? =
  19. 19.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
  20. 20.🧮 Two resistors in parallel give a total that is … (a) always zero (b) more than either one (c) their sum (d) less than either one
  21. 21.📏 How many amperes (A) is 160 mA? =
  22. 22.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
  23. 23.🧩 Which component has coloured bands? (a) fuse (b) thermistor (c) resistor (d) transistor
  24. 24.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 1 hour. How many watt-hours (Wh) are saved?
  25. 25.🔺 A 25 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
  26. 26.⚡ A device works on 6 V and takes 1.5 A. What is its power (in watts)? =
  27. 27.📏 How many watts (W) is 1.4 kW?
  28. 28.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) gets smaller (d) stays the same
  29. 29.True or false: a transistor smooths a wobbly supply. (a) False (b) True
  30. 30.📏 How many kilowatts (kW) is 4950 W? =
  31. 31.📏 How many milliamperes (mA) is 0.91 A?
  32. 32.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
  33. 33.🔍 Which is the odd one out? (a) switch off empty rooms (b) use old filament bulbs (c) unplug idle chargers (d) close the fridge quickly
  34. 34.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 72 Ω resistor? (a) violet-red-black (b) violet-red-brown (c) red-violet-black (d) grey-red-black
  35. 35.What does a fuse do? (a) makes things spin (b) blows if current is high (c) limits the current (d) turns a fan or wheels
  36. 36.What does an LED do? (a) limits the current (b) beeps for an alarm (c) boosts a small signal (d) glows using little power
  37. 37.⚡ A device works on 1.5 V and takes 3 A. What is its power (in watts)? =
  38. 38.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) does not light (b) may burn out (c) lights up
  39. 39.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  40. 40.🧮 A 100 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?

Answer key

  1. violet-black-black
  2. False
  3. I = V ÷ R
  4. 10
  5. 340
  6. 580
  7. 1.2
  8. voltmeter
  9. 5
  10. 0.2
  11. 5 %
  12. P = V × I
  13. the one nearest an end
  14. 7400
  15. R = V ÷ I
  16. anode (+)
  17. 0.6
  18. 0.1
  19. True
  20. less than either one
  21. 0.16
  22. 1.2
  23. resistor
  24. 63
  25. 2.5
  26. 9
  27. 1400
  28. gets smaller
  29. False
  30. 4.95
  31. 910
  32. 4.5
  33. use old filament bulbs
  34. violet-red-black
  35. blows if current is high
  36. glows using little power
  37. 4.5
  38. does not light
  39. 500
  40. 600

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