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Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 256 · 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 24 W device works on 12 V. What current does it take (in amperes)? =
  2. 2.🔺 A current of 0.2 A flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
  3. 3.Which of these is measured in ohms (Ω)? (a) voltage (b) resistance (c) power (d) the flow of charge
  4. 4.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
  5. 5.🧩 A capacitor in a circuit can … (a) store charge briefly (b) spin a wheel (c) make light (d) measure heat
  6. 6.🧮 A 20 V battery is joined to 12 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  7. 7.🧮 A 330 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
  8. 8.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  9. 9.Which of these wastes electricity? (a) unplug idle chargers (b) iron one shirt at a time (c) close the fridge quickly (d) use LED lamps
  10. 10.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 4 V supply. What current flows (in mA)?
  11. 11.🧮 A 5 V battery is joined to 2 Ω and 8 Ω resistors in series. What current flows (in amperes)? =
  12. 12.🔍 Which is the odd one out? (a) close the fridge quickly (b) run fans in empty rooms (c) iron one shirt at a time (d) use old filament bulbs
  13. 13.🧩 Which component senses how bright it is? (a) LDR (b) fuse (c) buzzer (d) LED
  14. 14.📏 In the water-pipe picture of a circuit, resistance is like … (a) the flow of water (b) a bigger tank (c) the water pressure (d) a narrow pipe
  15. 15.🔺 A current of 1 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  16. 16.💡 What does LED stand for? (a) light-emitting diode (b) large electric dial (c) low energy device (d) light energy dial
  17. 17.🧩 Which component blows if current is high? (a) LDR (b) fuse (c) resistor (d) thermistor
  18. 18.💡 Does it save or waste electricity to iron one shirt at a time? (a) wastes electricity (b) saves electricity
  19. 19.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 10 hours. How many watt-hours (Wh) are saved?
  21. 21.⚡ A 24 W device works on 24 V. What current does it take (in amperes)? =
  22. 22.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) their sum (c) less than either one (d) always zero
  23. 23.⚡ Which formula gives electric power? (a) P = V + I (b) P = V ÷ I (c) P = I ÷ V (d) P = V × I
  24. 24.🔺 In the V-I-R triangle, how do we find R? (a) R = V × I (b) R = I ÷ V (c) R = V + I (d) R = V ÷ I
  25. 25.⚡ A device works on 9 V and takes 1 A. What is its power (in watts)? =
  26. 26.🌈 A resistor has the colour bands white, red, yellow. What is its value in kilo-ohms (kΩ)? =
  27. 27.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 5 % (d) 25 %
  28. 28.🔺 A current of 20 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
  29. 29.🧮 An 18 V battery is joined to 6 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
  30. 30.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a motor (d) a fuse
  31. 31.🧮 Two equal 50 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  32. 32.🔍 Which is the odd one out? (a) use LED lamps (b) unplug idle chargers (c) leave the TV on standby (d) close the fridge quickly
  33. 33.⚡ Power tells us … (a) energy used each second (b) the size of a cell (c) the length of a wire (d) the colour of light
  34. 34.True or false: current is measured in amperes (A). (a) True (b) False
  35. 35.📏 How many kilo-ohms (kΩ) is 9600 Ω? =
  36. 36.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 100 (b) 1024 (c) 1000 (d) 10
  37. 37.Which of these saves electricity? (a) use daylight to read (b) iron one shirt at a time (c) leave fridge door open (d) run fans in empty rooms
  38. 38.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  39. 39.🌈 A resistor has the colour bands brown, orange, yellow. What is its value in kilo-ohms (kΩ)? =
  40. 40.🔍 Which is the odd one out? (a) unplug idle chargers (b) use LED lamps (c) close the fridge quickly (d) iron one shirt at a time

Answer key

  1. 2
  2. 12
  3. resistance
  4. saves electricity
  5. store charge briefly
  6. 1
  7. 355
  8. 345
  9. iron one shirt at a time
  10. 10
  11. 0.5
  12. close the fridge quickly
  13. LDR
  14. a narrow pipe
  15. 2
  16. light-emitting diode
  17. fuse
  18. wastes electricity
  19. 10
  20. 630
  21. 1
  22. less than either one
  23. P = V × I
  24. R = V ÷ I
  25. 9
  26. 920
  27. 5 %
  28. 6
  29. 1
  30. a motor
  31. 25
  32. leave the TV on standby
  33. energy used each second
  34. True
  35. 9.6
  36. 1000
  37. use daylight to read
  38. 500
  39. 130
  40. iron one shirt at a time

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