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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 318 · 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.

NameDateTime takenScore ___ / 40
  1. 1.⚡ 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
  2. 2.True or false: to leave fridge door open wastes electricity. (a) True (b) False
  3. 3.⚡ A home appliance on the 230 V mains takes 1 A. What is its power (in watts)?
  4. 4.🌈 A resistor has the colour bands brown, grey, yellow. What is its value in kilo-ohms (kΩ)? =
  5. 5.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.💡 Does it save or waste electricity to switch off empty rooms? (a) saves electricity (b) wastes electricity
  7. 7.🔺 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
  8. 8.🧩 Which component glows using little power? (a) LED (b) transistor (c) resistor (d) potentiometer
  9. 9.🔺 A 15 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
  10. 10.🔺 A current of 1.5 A flows when 4.5 V is joined across a resistor. What is its resistance (in ohms)?
  11. 11.⚡ A 0.75 W device works on 3 V. What current does it take (in amperes)? =
  12. 12.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  13. 13.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the gold band (d) the widest gap
  14. 14.🔺 A current of 1 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  15. 15.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
  16. 16.What does a buzzer do? (a) lets current go one way (b) limits the current (c) beeps for an alarm (d) makes things spin
  17. 17.🔺 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
  18. 18.🧾 A 100 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  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.True or false: a motor makes things spin. (a) False (b) True
  21. 21.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  22. 22.🧾 A 1000 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  23. 23.🧩 Which component boosts a small signal? (a) motor (b) thermistor (c) transistor (d) capacitor
  24. 24.🔺 A current of 50 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
  25. 25.⚡ A 0.3 W device works on 1.5 V. What current does it take (in amperes)? =
  26. 26.🧮 A 22 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  27. 27.🔺 A 0.4 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
  28. 28.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  29. 29.🌈 A resistor has the colour bands violet, black, orange. What is its value in kilo-ohms (kΩ)? =
  30. 30.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 5000 Ω resistor? (a) blue-green-red (b) green-black-red (c) green-black-orange (d) green-black-brown
  31. 31.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 900 Ω resistor? (a) white-black-red (b) white-black-brown (c) white-black-black (d) brown-white-brown
  32. 32.⚡ A 24 W device works on 12 V. What current does it take (in amperes)? =
  33. 33.🔺 A current of 1 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  34. 34.True or false: the voltmeter is joined in series. (a) False (b) True
  35. 35.⚡ A 24 W device works on 24 V. What current does it take (in amperes)? =
  36. 36.📏 In the water-pipe picture of a circuit, current is like … (a) the flow of water (b) the pipe colour (c) the water pressure (d) a narrow pipe
  37. 37.🔺 A 1.6 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
  38. 38.True or false: a resistor limits the current. (a) True (b) False
  39. 39.🧮 Two resistors in parallel give a total that is … (a) their sum (b) always zero (c) more than either one (d) less than either one
  40. 40.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a buzzer (d) a diode

Answer key

  1. energy used each second
  2. True
  3. 230
  4. 180
  5. 12.5
  6. saves electricity
  7. V = I × R
  8. LED
  9. 2.5
  10. 3
  11. 0.25
  12. 5
  13. the one nearest an end
  14. 3
  15. False
  16. beeps for an alarm
  17. gets smaller
  18. 0.8
  19. R = V ÷ I
  20. True
  21. 40
  22. 8
  23. transistor
  24. 7.5
  25. 0.2
  26. 132
  27. 0.2
  28. cathode (−)
  29. 70
  30. green-black-red
  31. white-black-brown
  32. 2
  33. 20
  34. False
  35. 1
  36. the flow of water
  37. 0.2
  38. True
  39. less than either one
  40. a buzzer

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