← Part 2 test: components and Ohm’s law lesson New set →

Electronics Worksheet: Components and Ohm’s Law Test

Electronics lesson 20: Part 2 test: components and Ohm’s law · Set 975 · 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.🔺 A 0.8 V supply is joined across a 4 Ω resistor. What current flows (in amperes)? =
  2. 2.Which of these wastes electricity? (a) switch off empty rooms (b) close the fridge quickly (c) leave the TV on standby (d) use LED lamps
  3. 3.What does an LED do? (a) stores a little charge (b) smooths a wobbly supply (c) glows using little power (d) blows if current is high
  4. 4.🧮 Five equal 25 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  5. 5.💡 A red LED uses 2 V and should get 20 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
  6. 6.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to make it brighter (d) to change its colour
  7. 7.🌈 In the resistor colour code, which number does grey stand for?
  8. 8.🔺 A current of 2 A flows through an 8 Ω resistor. What is the voltage across it (in volts)? =
  9. 9.⚡ Power tells us … (a) the colour of light (b) the length of a wire (c) the size of a cell (d) energy used each second
  10. 10.🧩 Which part changes electrical energy into sound? (a) a resistor (b) a capacitor (c) a diode (d) a buzzer
  11. 11.💡 A red LED (it uses 2 V) is joined with a 300 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  12. 12.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  13. 13.True or false: on an LED, the round-side leg is the cathode (−). (a) True (b) False
  14. 14.🧩 A capacitor in a circuit can … (a) make light (b) store charge briefly (c) measure heat (d) spin a wheel
  15. 15.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) any band (d) the widest gap
  16. 16.🔺 A 1.2 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
  17. 17.🔺 A 3.75 V supply is joined across a 15 Ω resistor. What current flows (in amperes)? =
  18. 18.🧾 A 50 W appliance runs for 8 hours. How many units (kWh) of electricity does it use? =
  19. 19.🔺 A current of 25 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
  20. 20.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
  21. 21.💡 A red LED uses 2 V and should get 10 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
  22. 22.🧮 A 2.25 V battery is joined to 3 Ω and 6 Ω resistors in series. What current flows (in amperes)? =
  23. 23.🌈 A resistor has the colour bands white, red, red. What is its value in kilo-ohms (kΩ)? =
  24. 24.🧮 Two equal 1000 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  25. 25.True or false: to leave fridge door open saves electricity. (a) True (b) False
  26. 26.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 9 hours. How many watt-hours (Wh) are saved?
  27. 27.🧮 Four equal 200 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  28. 28.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 5000 Ω resistor? (a) green-black-brown (b) green-black-red (c) green-black-orange (d) blue-green-red
  29. 29.📏 Voltmeter or ammeter: which one is joined across a part? (a) voltmeter (b) ammeter
  30. 30.🔺 A current of 0.25 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
  31. 31.True or false: the voltmeter measures current. (a) True (b) False
  32. 32.🧮 Four equal 100 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
  33. 33.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3 V supply. What current flows (in mA)?
  34. 34.🔍 Which is the odd one out? (a) use old filament bulbs (b) leave the TV on standby (c) set the AC to 24 °C (d) leave fridge door open
  35. 35.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 ampere (c) 1 watt (d) 1 volt
  36. 36.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
  37. 37.True or false: to use daylight to read saves electricity. (a) False (b) True
  38. 38.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
  39. 39.🌈 A resistor has the colour bands orange, green, yellow. What is its value in kilo-ohms (kΩ)? =
  40. 40.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) close the fridge quickly (c) use daylight to read (d) iron one shirt at a time

Answer key

  1. 0.2
  2. leave the TV on standby
  3. glows using little power
  4. 5
  5. 500
  6. to limit the current
  7. 8
  8. 16
  9. energy used each second
  10. a buzzer
  11. 5
  12. anode (+)
  13. False
  14. store charge briefly
  15. the one nearest an end
  16. 0.1
  17. 0.25
  18. 0.4
  19. 12.5
  20. ammeter
  21. 300
  22. 0.25
  23. 9.2
  24. 500
  25. False
  26. 567
  27. 50
  28. green-black-red
  29. voltmeter
  30. 1.5
  31. False
  32. 25
  33. 10
  34. set the AC to 24 °C
  35. 1 kilowatt-hour (kWh)
  36. 460
  37. True
  38. 2300
  39. 350
  40. iron one shirt at a time

Free electronics lessons, practice and worksheets at talentjr.in/electronics-for-kids