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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 464 · 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.🌈 In the resistor colour code, which number does white stand for?
  2. 2.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  3. 3.Which of these is measured in ohms (Ω)? (a) voltage (b) resistance (c) power (d) the push of a cell
  4. 4.🧩 Which part changes electrical energy into movement? (a) a motor (b) a fuse (c) a resistor (d) an LED
  5. 5.True or false: the voltmeter measures voltage. (a) False (b) True
  6. 6.🌈 A resistor has the colour bands red, violet, orange. What is its value (in ohms)?
  7. 7.True or false: a resistor limits the current. (a) False (b) True
  8. 8.🧮 Two equal 470 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  9. 9.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  10. 10.🧮 Resistors of 470 Ω and 470 Ω are joined in series. What is the total resistance (in ohms)?
  11. 11.⚡ A device works on 3 V and takes 1 A. What is its power (in watts)? =
  12. 12.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = R ÷ I (c) V = I × R (d) V = I ÷ R
  13. 13.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  14. 14.⚡ A device works on 24 V and takes 1.5 A. What is its power (in watts)? =
  15. 15.📏 Which unit measures the push of a cell? (a) ohm (Ω) (b) watt (W) (c) ampere (A) (d) volt (V)
  16. 16.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  17. 17.🧩 A capacitor in a circuit can … (a) measure heat (b) make light (c) spin a wheel (d) store charge briefly
  18. 18.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 0 % (d) 25 %
  19. 19.What does a capacitor do? (a) makes things spin (b) beeps for an alarm (c) makes a beeping sound (d) stores a little charge
  20. 20.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  21. 21.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
  22. 22.🔺 A current of 2.5 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it makes a sound (c) it does not light (d) it lights brighter
  24. 24.True or false: to set the AC to 24 °C saves electricity. (a) True (b) False
  25. 25.True or false: the voltmeter is joined in series. (a) False (b) True
  26. 26.🧮 A 1 V battery is joined to 4 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  27. 27.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🔺 An 11 V supply is joined across a 220 Ω resistor. What current flows (in milliamperes, mA)?
  29. 29.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🧮 Two equal 220 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  31. 31.What does an LDR do? (a) senses how hot it is (b) boosts a small signal (c) senses how bright it is (d) stores a little charge
  32. 32.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 5 V supply. What current flows (in mA)?
  33. 33.⚡ A device works on 5 V and takes 1.5 A. What is its power (in watts)? =
  34. 34.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.💡 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) does not light (b) lights up (c) may burn out
  36. 36.💡 An LED is joined to a 5 V battery through a 330 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  37. 37.🔺 A 0.5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  38. 38.🌈 In the resistor colour code, which number does green stand for?
  39. 39.🔺 A current of 2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.⚡ A device works on 6 V and takes 1 A. What is its power (in watts)? =

Answer key

  1. 9
  2. cathode (−)
  3. resistance
  4. a motor
  5. True
  6. 27000
  7. True
  8. 235
  9. cathode (−)
  10. 940
  11. 3
  12. V = I × R
  13. 1.25
  14. 36
  15. volt (V)
  16. True
  17. store charge briefly
  18. 5 %
  19. stores a little charge
  20. 900
  21. energy used each second
  22. 20
  23. it does not light
  24. True
  25. False
  26. 0.1
  27. 10
  28. 50
  29. 6
  30. 110
  31. senses how bright it is
  32. 20
  33. 7.5
  34. 10
  35. may burn out
  36. lights up
  37. 0.25
  38. 5
  39. 30
  40. 6

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