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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 585 · 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 resistor colour code, which number does green stand for?
  2. 2.🧾 A 100 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  3. 3.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
  4. 4.🧩 Which component has coloured bands? (a) capacitor (b) resistor (c) LDR (d) motor
  5. 5.🔺 A current of 1 A flows when 4 V is joined across a resistor. What is its resistance (in ohms)?
  6. 6.💡 An LED is joined to a 5 V battery through a 470 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) may burn out (b) lights up (c) does not light
  7. 7.🔺 A current of 25 mA flows when 3.75 V is joined across a resistor. What is its resistance (in ohms)?
  8. 8.What does a resistor do? (a) makes a beeping sound (b) has coloured bands (c) turns a fan or wheels (d) is a resistance knob
  9. 9.🔺 A current of 40 mA flows when 8.8 V is joined across a resistor. What is its resistance (in ohms)?
  10. 10.🔺 A current of 2.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
  11. 11.🧩 Which component beeps for an alarm? (a) buzzer (b) thermistor (c) resistor (d) LED
  12. 12.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V × I (c) P = V ÷ I (d) P = V + I
  13. 13.🔍 Which is the odd one out? (a) use daylight to read (b) leave the TV on standby (c) leave fridge door open (d) iron one shirt at a time
  14. 14.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 18000 Ω resistor? (a) brown-grey-red (b) brown-grey-orange (c) grey-brown-orange (d) brown-grey-yellow
  15. 15.📏 How many milliamperes (mA) is 0.83 A?
  16. 16.🌈 A resistor has the colour bands orange, orange, brown. What is its value (in ohms)?
  17. 17.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a diode (c) a buzzer (d) a capacitor
  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) True (b) False
  20. 20.🧮 Two equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  21. 21.🧮 Two equal 10 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  22. 22.🌈 A resistor has the colour bands red, brown, orange. What is its value in kilo-ohms (kΩ)? =
  23. 23.🔺 A current of 10 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.True or false: on an LED, the longer leg is the cathode (−). (a) False (b) True
  25. 25.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) gets bigger (d) becomes zero
  26. 26.Which of these saves electricity? (a) leave fridge door open (b) iron one shirt at a time (c) run fans in empty rooms (d) set the AC to 24 °C
  27. 27.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =
  28. 28.🔺 A 2 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
  29. 29.🧾 A 200 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
  30. 30.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 6 V supply. What current flows (in mA)?
  31. 31.True or false: a thermistor senses how bright it is. (a) True (b) False
  32. 32.🧾 A 60 W filament bulb is swapped for a 9 W LED lamp that gives about the same light. Both would run for 3 hours. How many watt-hours (Wh) are saved?
  33. 33.💡 What does LED stand for? (a) low energy device (b) light energy dial (c) large electric dial (d) light-emitting diode
  34. 34.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  35. 35.🌈 A resistor has the colour bands red, black, yellow. What is its value in kilo-ohms (kΩ)? =
  36. 36.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
  37. 37.🔺 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
  38. 38.🌈 Which band is read first on a resistor? (a) the one nearest an end (b) the gold band (c) any band (d) the widest gap
  39. 39.⚡ An 18 W device works on 9 V. What current does it take (in amperes)? =
  40. 40.🧮 A 17 V battery is joined to 12 Ω and 5 Ω resistors in series. What current flows (in amperes)? =

Answer key

  1. 5
  2. 0.8
  3. 10
  4. resistor
  5. 4
  6. does not light
  7. 150
  8. has coloured bands
  9. 220
  10. 50
  11. buzzer
  12. P = V × I
  13. use daylight to read
  14. brown-grey-orange
  15. 830
  16. 330
  17. a buzzer
  18. 2300
  19. True
  20. 100
  21. 5
  22. 21
  23. 1
  24. False
  25. gets smaller
  26. set the AC to 24 °C
  27. 0.375
  28. 0.1
  29. 0.8
  30. 20
  31. False
  32. 153
  33. light-emitting diode
  34. 3
  35. 200
  36. voltmeter
  37. I = V ÷ R
  38. the one nearest an end
  39. 2
  40. 1

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