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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 254 · 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.🔺 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
  2. 2.🔺 A 1.2 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  3. 3.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) stays the same (c) becomes zero (d) gets bigger
  4. 4.💡 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
  5. 5.🔺 A current of 20 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🔺 An 11.75 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  7. 7.🧮 A 1 V battery is joined to 3 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
  8. 8.🔺 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
  9. 9.🔺 A 0.6 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  10. 10.🌈 A resistor has the colour bands white, red, brown. What is its value (in ohms)?
  11. 11.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
  12. 12.🔺 A current of 25 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  13. 13.⚡ A home appliance on the 230 V mains takes 5 A. What is its power (in watts)?
  14. 14.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
  15. 15.🔺 A current of 1.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.🧾 Which lamp gives the same light for the least power? (a) an LED lamp (b) a candle (c) an oil lamp (d) a filament bulb
  17. 17.🌈 A resistor has the colour bands grey, white, orange. What is its value (in ohms)?
  18. 18.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
  19. 19.💡 A red LED uses 2 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
  20. 20.🔺 A current of 0.1 A flows when 0.5 V is joined across a resistor. What is its resistance (in ohms)?
  21. 21.🔺 A 2.4 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  22. 22.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 5 V supply. What current flows (in mA)?
  23. 23.Which of these is measured in ohms (Ω)? (a) power (b) how much a part resists (c) the push of a cell (d) energy used each second
  24. 24.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
  26. 26.🔺 A current of 3 A flows when 36 V is joined across a resistor. What is its resistance (in ohms)?
  27. 27.True or false: a fuse blows if current is high. (a) False (b) True
  28. 28.True or false: the ammeter measures current. (a) True (b) False
  29. 29.True or false: the ammeter is joined in series. (a) False (b) True
  30. 30.🔺 A 3 V supply is joined across a 3 Ω resistor. What current flows (in amperes)? =
  31. 31.🔺 A 7.5 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
  32. 32.🌈 A resistor has the colour bands red, orange, red. What is its value (in ohms)?
  33. 33.True or false: a thermistor beeps for an alarm. (a) True (b) False
  34. 34.True or false: a resistor limits the current. (a) False (b) True
  35. 35.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) lights up (b) may burn out (c) does not light
  36. 36.🧩 Which component beeps for an alarm? (a) fuse (b) thermistor (c) buzzer (d) diode
  37. 37.🌈 A resistor has the colour bands brown, violet, brown. What is its value (in ohms)?
  38. 38.🌈 A resistor has the colour bands brown, yellow, red. What is its value (in ohms)?
  39. 39.True or false: to leave the TV on standby wastes electricity. (a) False (b) True
  40. 40.🌈 A resistor has the colour bands green, black, orange. What is its value (in ohms)?

Answer key

  1. V = I × R
  2. 10
  3. gets smaller
  4. to limit the current
  5. 5
  6. 25
  7. 0.2
  8. R = V ÷ I
  9. 0.1
  10. 920
  11. 40
  12. 3.75
  13. 1150
  14. 15
  15. 9
  16. an LED lamp
  17. 89000
  18. True
  19. 280
  20. 5
  21. 0.2
  22. 20
  23. how much a part resists
  24. 18.8
  25. 1840
  26. 12
  27. True
  28. True
  29. True
  30. 1
  31. 50
  32. 2300
  33. False
  34. True
  35. may burn out
  36. buzzer
  37. 170
  38. 1400
  39. True
  40. 50000

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