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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 298 · 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 grey, yellow, red. What is its value in kilo-ohms (kΩ)? =
  2. 2.🔺 A 4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  3. 3.🔺 A current of 10 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🔺 In the V-I-R triangle, how do we find R? (a) R = V ÷ I (b) R = V + I (c) R = I ÷ V (d) R = V × I
  5. 5.💡 An LED is joined to a 6 V battery with no 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
  6. 6.🔺 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
  7. 7.🔺 A current of 2.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  8. 8.True or false: the voltmeter is joined in series. (a) False (b) True
  9. 9.🔺 A current of 1.5 A flows when 6 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.⚡ A 3 W device works on 12 V. What current does it take (in amperes)? =
  12. 12.🔺 A 10 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
  13. 13.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) becomes zero (c) gets bigger (d) gets smaller
  14. 14.📏 How many amperes (A) is 490 mA? =
  15. 15.🧮 Four equal 400 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 11000 Ω resistor? (a) brown-brown-yellow (b) brown-red-orange (c) brown-brown-orange (d) brown-brown-red
  17. 17.🧮 Two resistors in parallel give a total that is … (a) less than either one (b) more than either one (c) always zero (d) their sum
  18. 18.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) stay the same (c) smaller (d) zero
  19. 19.🧩 Which part changes electrical energy into sound? (a) a diode (b) a capacitor (c) a buzzer (d) a resistor
  20. 20.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 870 Ω resistor? (a) grey-violet-red (b) grey-violet-brown (c) violet-grey-brown (d) grey-violet-black
  21. 21.💡 An LED is joined to a 3 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) lights up (c) does not light
  22. 22.What does a thermistor do? (a) lets current go one way (b) blows if current is high (c) senses how hot it is (d) smooths a wobbly supply
  23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 88000 Ω resistor? (a) grey-grey-yellow (b) grey-grey-orange (c) grey-white-orange (d) grey-grey-red
  24. 24.⚡ A 0.6 W device works on 3 V. What current does it take (in amperes)? =
  25. 25.🔍 Which is the odd one out? (a) leave the TV on standby (b) leave fridge door open (c) use old filament bulbs (d) switch off empty rooms
  26. 26.💡 Does it save or waste electricity to switch off empty rooms? (a) wastes electricity (b) saves electricity
  27. 27.⚡ Which formula gives electric power? (a) P = V + I (b) P = I ÷ V (c) P = V ÷ I (d) P = V × I
  28. 28.🔺 A current of 2 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  29. 29.Which of these wastes electricity? (a) run fans in empty rooms (b) set the AC to 24 °C (c) use daylight to read (d) switch off empty rooms
  30. 30.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
  31. 31.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 2.5 V supply. What current flows (in mA)?
  32. 32.📏 How many amperes (A) is 1810 mA? =
  33. 33.🌈 A resistor has the colour bands white, yellow, orange. What is its value in kilo-ohms (kΩ)? =
  34. 34.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
  35. 35.🔺 A current of 2.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a narrow pipe (c) the water pressure (d) a bigger tank
  37. 37.💡 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) lights up (b) does not light (c) may burn out
  38. 38.💡 Does it save or waste electricity to leave fridge door open? (a) saves electricity (b) wastes electricity
  39. 39.What does an LED do? (a) lets current go one way (b) glows using little power (c) turns a fan or wheels (d) smooths a wobbly supply
  40. 40.⚡ Power tells us … (a) the colour of light (b) energy used each second (c) the size of a cell (d) the length of a wire

Answer key

  1. 8.4
  2. 2
  3. 1.2
  4. R = V ÷ I
  5. may burn out
  6. I = V ÷ R
  7. 7.5
  8. False
  9. 4
  10. 2
  11. 0.25
  12. 50
  13. gets smaller
  14. 0.49
  15. 100
  16. brown-brown-orange
  17. less than either one
  18. bigger
  19. a buzzer
  20. grey-violet-brown
  21. lights up
  22. senses how hot it is
  23. grey-grey-orange
  24. 0.2
  25. switch off empty rooms
  26. saves electricity
  27. P = V × I
  28. 15
  29. run fans in empty rooms
  30. 115
  31. 5
  32. 1.81
  33. 94
  34. 1.2
  35. 30
  36. a narrow pipe
  37. may burn out
  38. wastes electricity
  39. glows using little power
  40. energy used each second

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