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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 457 · 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.🧮 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
  2. 2.True or false: a transistor glows using little power. (a) True (b) False
  3. 3.🧾 A 2000 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
  4. 4.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  5. 5.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 1024 (b) 100 (c) 1000 (d) 10
  6. 6.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  7. 7.True or false: a capacitor blows if current is high. (a) True (b) False
  8. 8.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
  9. 9.🌈 A resistor has the colour bands blue, white, black. What is its value (in ohms)?
  10. 10.🔺 A current of 0.5 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.🧮 Three equal 75 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  12. 12.Which of these wastes electricity? (a) set the AC to 24 °C (b) switch off empty rooms (c) leave the TV on standby (d) use LED lamps
  13. 13.🔺 A 9.4 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  14. 14.🌈 In the resistor colour code, which number does white stand for?
  15. 15.⚡ Which formula gives electric power? (a) P = V + I (b) P = V × I (c) P = V ÷ I (d) P = I ÷ V
  16. 16.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets bigger (c) gets smaller (d) stays the same
  17. 17.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
  18. 18.Which of these saves electricity? (a) use old filament bulbs (b) use LED lamps (c) iron one shirt at a time (d) leave the TV on standby
  19. 19.🔺 A current of 0.1 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  20. 20.🔺 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
  21. 21.🔺 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
  22. 22.⚡ A 1.5 W device works on 3 V. What current does it take (in amperes)? =
  23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 5400 Ω resistor? (a) yellow-green-red (b) green-yellow-orange (c) green-yellow-red (d) green-yellow-brown
  24. 24.⚡ A device works on 24 V and takes 0.25 A. What is its power (in watts)? =
  25. 25.True or false: power is measured in volts (V). (a) True (b) False
  26. 26.⚡ A 0.375 W device works on 1.5 V. What current does it take (in amperes)? =
  27. 27.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) low energy device (d) light energy dial
  28. 28.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  29. 29.💡 Does it save or waste electricity to set the AC to 24 °C? (a) wastes electricity (b) saves electricity
  30. 30.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) any band (d) the one nearest an end
  31. 31.🧮 A 0.7 V battery is joined to 5 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  32. 32.True or false: the push of a cell is measured in amperes (A). (a) True (b) False
  33. 33.🔺 A 0.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  34. 34.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
  35. 35.True or false: the push of a cell is measured in volts (V). (a) True (b) False
  36. 36.🌈 A resistor has the colour bands green, black, brown. What is its value (in ohms)?
  37. 37.True or false: a capacitor smooths a wobbly supply. (a) True (b) False
  38. 38.True or false: resistance is measured in ohms (Ω). (a) True (b) False
  39. 39.🔺 A 2.5 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
  40. 40.🔺 A 20 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?

Answer key

  1. less than either one
  2. False
  3. 12
  4. 300
  5. 1000
  6. 5
  7. False
  8. True
  9. 69
  10. 8
  11. 25
  12. leave the TV on standby
  13. 20
  14. 9
  15. P = V × I
  16. gets smaller
  17. 5
  18. use LED lamps
  19. 12
  20. I = V ÷ R
  21. V = I × R
  22. 0.5
  23. green-yellow-red
  24. 6
  25. False
  26. 0.25
  27. light-emitting diode
  28. cathode (−)
  29. saves electricity
  30. the one nearest an end
  31. 0.1
  32. False
  33. 0.1
  34. 330
  35. True
  36. 500
  37. True
  38. True
  39. 0.5
  40. 50

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