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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 156 · 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 resistor has the colour bands blue, blue, black. What is its value (in ohms)?
  2. 2.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  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.True or false: a fuse blows if current is high. (a) True (b) False
  5. 5.💡 An LED is joined to a 9 V battery through a 1000 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) does not light (c) lights up
  6. 6.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🧮 Three equal 30 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  8. 8.🌈 In the resistor colour code, which number does red stand for?
  9. 9.🧮 A 100 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)?
  10. 10.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
  11. 11.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) gets smaller (d) stays the same
  12. 12.What does a buzzer do? (a) makes a beeping sound (b) lets current go one way (c) limits the current (d) boosts a small signal
  13. 13.⚡ A device works on 3 V and takes 1.5 A. What is its power (in watts)? =
  14. 14.🔺 A current of 10 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  16. 16.True or false: to use LED lamps wastes electricity. (a) True (b) False
  17. 17.💡 An LED is joined to a 5 V battery through a 470 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) does not light (c) lights up
  18. 18.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  19. 19.🧩 Which part changes electrical energy into sound? (a) a diode (b) a buzzer (c) a capacitor (d) a resistor
  20. 20.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) energy used each second (d) the size of a cell
  21. 21.🧩 Which component lets current go one way? (a) buzzer (b) capacitor (c) resistor (d) diode
  22. 22.🔺 A 1 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  23. 23.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 50 % (d) 5 %
  24. 24.What does an LDR do? (a) blows if current is high (b) lets current go one way (c) makes a beeping sound (d) senses how bright it is
  25. 25.🧩 Which component blows if current is high? (a) transistor (b) LDR (c) diode (d) fuse
  26. 26.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  27. 27.🔺 A 16.5 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  28. 28.Which of these is measured in amperes (A)? (a) the flow of charge (b) voltage (c) resistance (d) the push of a cell
  29. 29.💡 Does it save or waste electricity to use old filament bulbs? (a) wastes electricity (b) saves electricity
  30. 30.🧮 Five equal 125 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  31. 31.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  32. 32.🌈 A resistor has the colour bands green, brown, brown. What is its value (in ohms)?
  33. 33.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  34. 34.What does a capacitor do? (a) limits the current (b) blows if current is high (c) stores a little charge (d) beeps for an alarm
  35. 35.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  36. 36.⚡ A 0.6 W device works on 6 V. What current does it take (in amperes)? =
  37. 37.💡 An LED is joined to a 3 V battery through a 1000 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  38. 38.⚡ A 6 W device works on 6 V. What current does it take (in amperes)? =
  39. 39.📏 How many watts (W) is 4.2 kW?
  40. 40.💡 What happens if an LED is put in backwards? (a) it does not light (b) it lights brighter (c) it makes a sound (d) it changes colour

Answer key

  1. 66
  2. 10
  3. I = V ÷ R
  4. True
  5. does not light
  6. 100
  7. 10
  8. 2
  9. 120
  10. saves electricity
  11. gets smaller
  12. makes a beeping sound
  13. 4.5
  14. 2.5
  15. 345
  16. False
  17. does not light
  18. 5
  19. a buzzer
  20. energy used each second
  21. diode
  22. 0.2
  23. 5 %
  24. senses how bright it is
  25. fuse
  26. cathode (−)
  27. 50
  28. the flow of charge
  29. wastes electricity
  30. 25
  31. voltmeter
  32. 510
  33. 50
  34. stores a little charge
  35. 50
  36. 0.1
  37. lights up
  38. 1
  39. 4200
  40. it does not light

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