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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 15 · 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.🔺 A current of 20 mA flows when 6.6 V is joined across a resistor. What is its resistance (in ohms)?
  2. 2.🌈 A resistor has the colour bands grey, black, orange. What is its value (in ohms)?
  3. 3.🧩 Which component lets current go one way? (a) diode (b) thermistor (c) buzzer (d) resistor
  4. 4.🔺 A current of 0.25 A flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
  5. 5.🔺 A current of 20 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🔺 A current of 0.1 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
  7. 7.🔺 A current of 3 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7600 Ω resistor? (a) violet-blue-brown (b) violet-blue-red (c) violet-blue-orange (d) blue-violet-red
  9. 9.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  10. 10.What does a transistor do? (a) is a resistance knob (b) lets current go one way (c) stores a little charge (d) boosts a small signal
  11. 11.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
  12. 12.🔺 A 2 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
  13. 13.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 350 Ω resistor? (a) green-orange-brown (b) orange-green-red (c) orange-green-brown (d) orange-green-black
  14. 14.True or false: energy used each second is measured in watts (W). (a) False (b) True
  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.Which of these wastes electricity? (a) run fans in empty rooms (b) switch off empty rooms (c) close the fridge quickly (d) use daylight to read
  17. 17.🔺 A 25 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  18. 18.🧾 A family uses 170 units of electricity in a month and each unit costs ₹8. What is the bill (in ₹)?
  19. 19.🔺 An 18.8 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
  20. 20.🌈 In the resistor colour code, which number does white stand for?
  21. 21.True or false: the voltmeter is joined in series. (a) False (b) True
  22. 22.🔺 A current of 1.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
  23. 23.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🔺 A 16 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
  25. 25.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  26. 26.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  27. 27.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 50 % (c) 5 % (d) 0 %
  28. 28.⚡ A device works on 9 V and takes 3 A. What is its power (in watts)? =
  29. 29.🌈 A resistor has the colour bands red, grey, red. What is its value in kilo-ohms (kΩ)? =
  30. 30.💡 Why does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to store charge (d) to limit the current
  31. 31.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I × R (c) V = R ÷ I (d) V = I + R
  32. 32.🧩 Which component boosts a small signal? (a) LDR (b) transistor (c) motor (d) diode
  33. 33.🌈 A resistor has the colour bands yellow, orange, red. What is its value in kilo-ohms (kΩ)? =
  34. 34.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
  35. 35.🧮 Four equal 80 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  36. 36.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) gets smaller (c) stays the same (d) gets bigger
  37. 37.🔺 A current of 0.2 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
  38. 38.🔺 A current of 10 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  39. 39.📏 Which unit measures power? (a) ampere (A) (b) ohm (Ω) (c) volt (V) (d) watt (W)
  40. 40.🧮 Five equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?

Answer key

  1. 330
  2. 80000
  3. diode
  4. 12
  5. 10
  6. 12
  7. 4
  8. violet-blue-red
  9. 100
  10. boosts a small signal
  11. saves electricity
  12. 20
  13. orange-green-brown
  14. True
  15. P = V × I
  16. run fans in empty rooms
  17. 50
  18. 1360
  19. 40
  20. 9
  21. False
  22. 6
  23. 10
  24. 40
  25. 10
  26. cathode (−)
  27. 5 %
  28. 27
  29. 2.8
  30. to limit the current
  31. V = I × R
  32. transistor
  33. 4.3
  34. cathode (−)
  35. 20
  36. gets smaller
  37. 5
  38. 2
  39. watt (W)
  40. 20

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