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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 257 · 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.⚡ Power tells us … (a) the size of a cell (b) the length of a wire (c) energy used each second (d) the colour of light
  2. 2.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
  4. 4.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 140 Ω resistor? (a) brown-yellow-brown (b) brown-yellow-red (c) brown-yellow-black (d) yellow-brown-brown
  5. 5.🧾 A 100 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  6. 6.🔺 A current of 2 A flows when 24 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🧮 Resistors of 150 Ω, 220 Ω, 22 Ω and 50 Ω are joined in series. What is the total resistance (in ohms)?
  8. 8.🧮 Five equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  9. 9.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  10. 10.⚡ A 3 W device works on 12 V. What current does it take (in amperes)? =
  11. 11.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  12. 12.🔺 A 6 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  13. 13.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  14. 14.🔺 A 6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  15. 15.🧮 Two resistors in parallel give a total that is … (a) their sum (b) more than either one (c) less than either one (d) always zero
  16. 16.🔺 A current of 10 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  17. 17.💡 What happens if an LED is put in backwards? (a) it makes a sound (b) it does not light (c) it changes colour (d) it lights brighter
  18. 18.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  19. 19.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V × I (c) R = V ÷ I (d) R = V + I
  20. 20.Which of these is measured in volts (V)? (a) energy used each second (b) voltage (c) how much a part resists (d) the flow of charge
  21. 21.🧾 A family uses 190 units of electricity in a month and each unit costs ₹6. What is the bill (in ₹)?
  22. 22.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) lights up (c) may burn out
  23. 23.🔺 A current of 0.5 A flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
  24. 24.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.🔺 A 0.2 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  26. 26.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) stay the same (d) smaller
  27. 27.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to make it brighter (c) to store charge (d) to change its colour
  28. 28.🔺 A 6 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  29. 29.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  30. 30.🔺 A current of 0.1 A flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
  31. 31.🌈 A resistor has the colour bands red, blue, orange. What is its value (in ohms)?
  32. 32.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
  33. 33.True or false: a capacitor lets current go one way. (a) False (b) True
  34. 34.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
  35. 35.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 0 % (d) 25 %
  36. 36.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I × R (c) V = I + R (d) V = I ÷ R
  37. 37.💡 What does LED stand for? (a) large electric dial (b) light-emitting diode (c) low energy device (d) light energy dial
  38. 38.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  39. 39.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  40. 40.💡 Does it save or waste electricity to use daylight to read? (a) wastes electricity (b) saves electricity

Answer key

  1. energy used each second
  2. 2.5
  3. P = V × I
  4. brown-yellow-brown
  5. 0.2
  6. 12
  7. 442
  8. 10
  9. cathode (−)
  10. 0.25
  11. 3.75
  12. 40
  13. anode (+)
  14. 1
  15. less than either one
  16. 1.5
  17. it does not light
  18. 5
  19. R = V ÷ I
  20. voltage
  21. 1140
  22. lights up
  23. 15
  24. 1
  25. 0.1
  26. bigger
  27. to limit the current
  28. 2
  29. 5
  30. 20
  31. 26000
  32. 1.5
  33. False
  34. False
  35. 5 %
  36. V = I × R
  37. light-emitting diode
  38. cathode (−)
  39. 165
  40. saves electricity

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