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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 208 · 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.Which of these is measured in volts (V)? (a) how much a part resists (b) resistance (c) voltage (d) power
  2. 2.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  3. 3.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 kilowatt-hour (kWh) (c) 1 ampere (d) 1 watt
  4. 4.🧮 Resistors of 100 Ω, 330 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
  5. 5.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🌈 A resistor has the colour bands orange, orange, red. What is its value (in ohms)?
  7. 7.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets bigger (c) gets smaller (d) becomes zero
  8. 8.🧮 Two equal 330 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  9. 9.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  10. 10.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  11. 11.💡 An LED is joined to a 5 V battery with no 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
  12. 12.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  13. 13.💡 A red LED uses 2 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  14. 14.🧮 Two equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  15. 15.⚡ A 6 W device works on 12 V. What current does it take (in amperes)? =
  16. 16.🧾 A 500 W appliance runs for 2 hours. How many units (kWh) of electricity does it use? =
  17. 17.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  18. 18.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  19. 19.True or false: the ammeter is joined in series. (a) False (b) True
  20. 20.🔺 In the V-I-R triangle, how do we find I? (a) I = V ÷ R (b) I = V × R (c) I = R ÷ V (d) I = V + R
  21. 21.🔺 A current of 1.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.🔺 A current of 2 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  24. 24.🌈 In the resistor colour code, which number does orange stand for?
  25. 25.🔺 A 6 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
  26. 26.Which of these is measured in ohms (Ω)? (a) voltage (b) energy used each second (c) resistance (d) the flow of charge
  27. 27.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  28. 28.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to make it brighter (d) to store charge
  29. 29.🧩 Which part changes electrical energy into movement? (a) a resistor (b) an LED (c) a motor (d) a fuse
  30. 30.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
  31. 31.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 25 % (d) 5 %
  32. 32.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) does not light (c) lights up
  33. 33.What does an LED do? (a) boosts a small signal (b) has coloured bands (c) limits the current (d) glows using little power
  34. 34.🧮 A 33 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  35. 35.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  36. 36.True or false: the voltmeter measures voltage. (a) False (b) True
  37. 37.🧮 Five equal 250 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  38. 38.What does a thermistor do? (a) stores a little charge (b) glows using little power (c) makes a beeping sound (d) senses how hot it is
  39. 39.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
  40. 40.💡 An LED is joined to a 6 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) lights up (b) does not light (c) may burn out

Answer key

  1. voltage
  2. 0.6
  3. 1 kilowatt-hour (kWh)
  4. 760
  5. 1.25
  6. 3300
  7. gets smaller
  8. 165
  9. 5
  10. 0.2
  11. may burn out
  12. 200
  13. 350
  14. 20
  15. 0.5
  16. 1
  17. cathode (−)
  18. 2300
  19. True
  20. I = V ÷ R
  21. 6
  22. 24
  23. False
  24. 3
  25. 20
  26. resistance
  27. 10
  28. to limit the current
  29. a motor
  30. 1.2
  31. 5 %
  32. lights up
  33. glows using little power
  34. 43
  35. 50
  36. True
  37. 50
  38. senses how hot it is
  39. 40
  40. does not light

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