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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 678 · 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 gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 25 % (d) 0 %
  2. 2.🧮 A 330 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  3. 3.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  4. 4.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a capacitor (d) a buzzer
  5. 5.True or false: a buzzer makes a beeping sound. (a) True (b) False
  6. 6.📏 How many amperes (A) is 180 mA? =
  7. 7.What does a potentiometer do? (a) boosts a small signal (b) beeps for an alarm (c) is a resistance knob (d) lets current go one way
  8. 8.💡 An LED is joined to a 9 V battery through a 330 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) lights up (b) does not light (c) may burn out
  9. 9.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the size of a cell (d) the colour of light
  11. 11.True or false: a capacitor smooths a wobbly supply. (a) False (b) True
  12. 12.⚡ A device works on 24 V and takes 0.5 A. What is its power (in watts)? =
  13. 13.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = V ÷ R (d) I = R ÷ V
  14. 14.🔺 A current of 2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) gets bigger (c) becomes zero (d) stays the same
  16. 16.🔺 A current of 20 mA flows when 9.4 V is joined across a resistor. What is its resistance (in ohms)?
  17. 17.💡 An LED is joined to a 5 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) does not light (c) may burn out
  18. 18.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a resistor (c) a motor (d) an LED
  19. 19.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) their sum (d) always zero
  20. 20.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.🔺 A 0.6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  22. 22.Which of these is measured in watts (W)? (a) the push of a cell (b) voltage (c) resistance (d) power
  23. 23.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  24. 24.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  25. 25.🔺 A current of 25 mA flows through a 330 Ω resistor. What is the voltage across it (in volts)? =
  26. 26.⚡ A device works on 9 V and takes 2 A. What is its power (in watts)? =
  27. 27.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
  28. 28.🔺 An 18 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  29. 29.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  30. 30.What does an LED do? (a) is a resistance knob (b) beeps for an alarm (c) senses how bright it is (d) glows using little power
  31. 31.True or false: the ammeter measures current. (a) True (b) False
  32. 32.⚡ A 3 W device works on 3 V. What current does it take (in amperes)? =
  33. 33.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  34. 34.⚡ A device works on 5 V and takes 3 A. What is its power (in watts)? =
  35. 35.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = V ÷ I (d) P = I ÷ V
  36. 36.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) a filament bulb (d) an LED lamp
  37. 37.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 72000 Ω resistor? (a) red-violet-orange (b) violet-red-red (c) violet-red-yellow (d) violet-red-orange
  38. 38.⚡ A device works on 9 V and takes 3 A. What is its power (in watts)? =
  39. 39.🌈 In the resistor colour code, which number does violet stand for?
  40. 40.True or false: to run fans in empty rooms saves electricity. (a) True (b) False

Answer key

  1. 5 %
  2. 350
  3. 230
  4. a buzzer
  5. True
  6. 0.18
  7. is a resistance knob
  8. does not light
  9. 5
  10. energy used each second
  11. True
  12. 12
  13. I = V ÷ R
  14. 12
  15. gets smaller
  16. 470
  17. does not light
  18. a motor
  19. less than either one
  20. 1
  21. 0.1
  22. power
  23. cathode (−)
  24. 100
  25. 8.25
  26. 18
  27. 8.8
  28. 3
  29. 345
  30. glows using little power
  31. True
  32. 1
  33. anode (+)
  34. 15
  35. P = V × I
  36. an LED lamp
  37. violet-red-orange
  38. 27
  39. 7
  40. False

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