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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 782 · 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.🧮 Resistors of 100 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
  2. 2.🔺 An 8 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  3. 3.🧩 Which component limits the current? (a) LDR (b) motor (c) transistor (d) resistor
  4. 4.🌈 A resistor has the colour bands blue, orange, orange. What is its value (in ohms)?
  5. 5.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to an 8 V supply. What current flows (in mA)?
  6. 6.🧮 Two resistors in parallel give a total that is … (a) their sum (b) less than either one (c) always zero (d) more than either one
  7. 7.📏 Which unit measures current? (a) ohm (Ω) (b) ampere (A) (c) watt (W) (d) volt (V)
  8. 8.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  9. 9.🌈 In the resistor colour code, which number does white stand for?
  10. 10.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 86 Ω resistor? (a) blue-grey-black (b) grey-blue-brown (c) white-blue-black (d) grey-blue-black
  11. 11.🔺 A current of 0.25 A flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
  12. 12.🔍 Which is the odd one out? (a) close the fridge quickly (b) leave fridge door open (c) switch off empty rooms (d) set the AC to 24 °C
  13. 13.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 6800 Ω resistor? (a) blue-grey-orange (b) blue-grey-brown (c) blue-grey-red (d) grey-blue-red
  14. 14.🔺 A current of 1.5 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  16. 16.🔺 A current of 0.5 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 6300 Ω resistor? (a) blue-orange-orange (b) blue-orange-red (c) blue-orange-brown (d) orange-blue-red
  18. 18.🌈 A resistor has the colour bands violet, white, black. What is its value (in ohms)?
  19. 19.What does a fuse do? (a) blows if current is high (b) stores a little charge (c) is a resistance knob (d) limits the current
  20. 20.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  21. 21.🌈 In the resistor colour code, which number does red stand for?
  22. 22.📏 Which unit measures the push of a cell? (a) ampere (A) (b) watt (W) (c) ohm (Ω) (d) volt (V)
  23. 23.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
  24. 24.🔺 A 10 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  25. 25.🔺 In the V-I-R triangle, how do we find I? (a) I = R ÷ V (b) I = V × R (c) I = V + R (d) I = V ÷ R
  26. 26.🔺 An 18.8 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  27. 27.💡 On an LED, is the round-side leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  28. 28.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 570 Ω resistor? (a) green-violet-black (b) green-violet-red (c) green-violet-brown (d) violet-green-brown
  29. 29.🔺 A current of 50 mA flows when 23.5 V is joined across a resistor. What is its resistance (in ohms)?
  30. 30.🔺 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
  31. 31.🧩 Which component lets current go one way? (a) LED (b) diode (c) capacitor (d) motor
  32. 32.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) energy used each second (d) the size of a cell
  33. 33.⚡ A device works on 9 V and takes 0.5 A. What is its power (in watts)? =
  34. 34.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) bigger (c) smaller (d) stay the same
  35. 35.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to make it brighter (c) to store charge (d) to limit the current
  36. 36.🔺 A current of 50 mA flows when 11 V is joined across a resistor. What is its resistance (in ohms)?
  37. 37.📏 Voltmeter or ammeter: which one is joined in series? (a) ammeter (b) voltmeter
  38. 38.⚡ A device works on 6 V and takes 0.25 A. What is its power (in watts)? =
  39. 39.🔺 A current of 1.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.🔺 A 30 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =

Answer key

  1. 110
  2. 1
  3. resistor
  4. 63000
  5. 20
  6. less than either one
  7. ampere (A)
  8. 230
  9. 9
  10. grey-blue-black
  11. 10
  12. leave fridge door open
  13. blue-grey-red
  14. 7.5
  15. 300
  16. 7.5
  17. blue-orange-red
  18. 79
  19. blows if current is high
  20. 2
  21. 2
  22. volt (V)
  23. False
  24. 2.5
  25. I = V ÷ R
  26. 40
  27. anode (+)
  28. green-violet-brown
  29. 470
  30. gets smaller
  31. diode
  32. energy used each second
  33. 4.5
  34. bigger
  35. to limit the current
  36. 220
  37. ammeter
  38. 1.5
  39. 15
  40. 3

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