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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 919 · 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 resistor has the colour bands violet, green, red. What is its value in kilo-ohms (kΩ)? =
  2. 2.🔺 A current of 2 A flows when 24 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.📏 How many kilowatts (kW) is 100 W? =
  4. 4.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
  5. 5.🔺 A current of 1.5 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 18000 Ω resistor? (a) brown-grey-yellow (b) brown-grey-red (c) brown-grey-orange (d) grey-brown-orange
  7. 7.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) bigger (c) smaller (d) zero
  8. 8.🔺 A current of 2.5 A flows when 37.5 V is joined across a resistor. What is its resistance (in ohms)?
  9. 9.🔺 A current of 2 A flows when 30 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.🧩 Which component makes a beeping sound? (a) diode (b) capacitor (c) buzzer (d) potentiometer
  11. 11.🧩 Which part changes electrical energy into movement? (a) a motor (b) an LED (c) a resistor (d) a fuse
  12. 12.🧮 Resistors of 10 Ω, 150 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  13. 13.🧮 Resistors of 10 Ω, 150 Ω, 20 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
  14. 14.🔺 A 12.5 V supply is joined across a 500 Ω resistor. What current flows (in milliamperes, mA)?
  15. 15.🔺 A current of 1 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.💡 What happens if an LED is put in backwards? (a) it changes colour (b) it does not light (c) it makes a sound (d) it lights brighter
  17. 17.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 81 Ω resistor? (a) brown-grey-black (b) white-brown-black (c) grey-brown-brown (d) grey-brown-black
  18. 18.🔺 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
  19. 19.True or false: a transistor boosts a small signal. (a) False (b) True
  20. 20.🧾 A family uses 190 units of electricity in a month and each unit costs ₹7. What is the bill (in ₹)?
  21. 21.🔺 A current of 2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  22. 22.🌈 A resistor has the colour bands red, white, red. What is its value (in ohms)?
  23. 23.What does an LDR do? (a) is a resistance knob (b) limits the current (c) turns a fan or wheels (d) senses how bright it is
  24. 24.🔺 A current of 0.2 A flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  25. 25.💡 What does LED stand for? (a) light-emitting diode (b) light energy dial (c) low energy device (d) large electric dial
  26. 26.True or false: an LDR stores a little charge. (a) False (b) True
  27. 27.⚡ A 1.25 W device works on 5 V. What current does it take (in amperes)? =
  28. 28.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) stays the same (c) becomes zero (d) gets smaller
  30. 30.⚡ Power tells us … (a) the colour of light (b) the size of a cell (c) the length of a wire (d) energy used each second
  31. 31.🔺 A current of 25 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  32. 32.🔍 Which is the odd one out? (a) leave fridge door open (b) iron one shirt at a time (c) use old filament bulbs (d) set the AC to 24 °C
  33. 33.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  34. 34.🧮 Resistors of 470 Ω, 10 Ω and 220 Ω are joined in series. What is the total resistance (in ohms)?
  35. 35.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
  36. 36.🔺 A 2.5 V supply is joined across a 250 Ω resistor. What current flows (in milliamperes, mA)?
  37. 37.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  38. 38.What does a motor do? (a) blows if current is high (b) makes things spin (c) has coloured bands (d) is a resistance knob
  39. 39.💡 Does it save or waste electricity to use old filament bulbs? (a) saves electricity (b) wastes electricity
  40. 40.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I

Answer key

  1. 7.5
  2. 12
  3. 0.1
  4. True
  5. 4.5
  6. brown-grey-orange
  7. bigger
  8. 15
  9. 15
  10. buzzer
  11. a motor
  12. 193
  13. 213
  14. 25
  15. 10
  16. it does not light
  17. grey-brown-black
  18. R = V ÷ I
  19. True
  20. 1330
  21. 12
  22. 2900
  23. senses how bright it is
  24. 12
  25. light-emitting diode
  26. False
  27. 0.25
  28. 2
  29. gets smaller
  30. energy used each second
  31. 2.5
  32. set the AC to 24 °C
  33. voltmeter
  34. 700
  35. 18.8
  36. 10
  37. 0.4
  38. makes things spin
  39. wastes electricity
  40. P = V × I

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