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Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 478 · 40 questions
TalentJR

Remember (Find the topic, use the idea): Find the topic: circuit, safety, formula, component, program, sensor or IoT. Use that lesson’s rule — complete loop, V = I × R, P = V × I, last command wins, true → if part. Safety answers are always: low voltage, dry hands, an adult, never the mains.

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  1. 1.💡 4 identical bulbs are joined in parallel across a 4.5 V battery (ideal wires). How many volts does each bulb get? =
  2. 2.🧮 Adding another resistor in series makes the total resistance … (a) smaller (b) stay the same (c) bigger (d) zero
  3. 3.⚡ A device works on 1.5 V and takes 1 A. What is its power (in watts)? =
  4. 4.⏱️ loop forever { LED ON; wait 200 ms; LED OFF; wait 900 ms }
    How many milliseconds does one blink (ON + OFF) take?
  5. 5.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
  6. 6.⚙️ What is an actuator? (a) a battery (b) a program (c) a sensor (d) an output that acts
  7. 7.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 4.25 V supply. What current flows (in mA)?
  8. 8.⏱️ repeat 3 times { buzzer ON; wait 500 ms; buzzer OFF; wait 1000 ms }
    How many milliseconds does this take in all?
  9. 9.True or false: on a cell, “the flat end” means the − (negative) end. (a) True (b) False
  10. 10.🔌 Which metal is used for most electric wires at home? (a) copper (b) rubber (c) glass (d) plastic
  11. 11.📏 How many ohms make 1 kilo-ohm (kΩ)? (a) 10 (b) 100 (c) 1024 (d) 1000
  12. 12.What does a slide switch do? (a) stays where you flip it (b) slides side to side (c) flips up or down (d) closes when tipped over
  13. 13.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
  14. 14.⚠️ What protects home wiring by melting or tripping when too much current flows? (a) a bulb (b) a plug top (c) a long wire (d) a fuse or MCB
  15. 15.🧮 An 11 V battery is joined to 12 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
  16. 16.🔁 What must there be for a current to flow? (a) one loose end (b) a plastic gap (c) a broken path (d) a complete loop
  17. 17.💡 On an LED, is the longer leg the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
  18. 18.🌐 A soil sensor sends a reading to an app every 5 minutes. How many readings arrive in 1 hour?
  19. 19.🔦 A circuit has a new cell, a good bulb and a switch that is ON. All the wires are firmly joined. A gap in one wire is bridged by a safety pin. Does the bulb glow? (a) No (b) Yes
  20. 20.True or false: on a cell, “usually the red wire” means the + (positive) end. (a) False (b) True
  21. 21.🌐 Each reading a sensor sends is 10 bytes. How many bytes do 170 readings take?
  22. 22.Which of these wastes electricity? (a) unplug idle chargers (b) run fans in empty rooms (c) use daylight to read (d) set the AC to 24 °C
  23. 23.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
  24. 24.🌐 A soil sensor sends a reading to an app every 5 minutes. How many readings arrive in 3 hours?
  25. 25.⏱️ repeat 5 times { buzzer ON; wait 200 ms; buzzer OFF; wait 400 ms }
    How many milliseconds does this take in all?
  26. 26.🔘 Switch A is on the main wire next to the cell and the bulb; then the wire splits into two side-by-side paths, one with switch B and one with switch C. A is ON, B is ON and C is OFF. Does the bulb glow? (a) Yes (b) No
  27. 27.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
  28. 28.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
  29. 29.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V ÷ I (d) P = V × I
  30. 30.🔍 Which is the odd one out? (a) leave the TV on standby (b) use old filament bulbs (c) set the AC to 24 °C (d) run fans in empty rooms
  31. 31.True or false: on a cell, “the longer symbol line” means the + (positive) end. (a) True (b) False
  32. 32.🔐 Why install updates on IoT devices? (a) they fix security holes (b) they change the colour (c) they make it heavier (d) they delete the Wi-Fi
  33. 33.🔁 total = 0
    for i = 1 to 5 { total = total + i }
    What is total at the end?
  34. 34.💡 An LED (with its resistor) is on pin 8. All pins start LOW. The program runs once:
    set pin 7 LOW
    set pin 7 LOW
    set pin 7 LOW
    set pin 7 LOW
    set pin 7 LOW
    Is the LED ON or OFF at the end?     (a) OFF (b) ON
  35. 35.🔍 Which is the odd one out? (a) a push button (b) a light sensor (c) a turning knob (d) a motor
  36. 36.True or false: “how loud a sound is” is a digital signal. (a) True (b) False
  37. 37.✏️ In a cell symbol, which line is the + terminal? (a) both lines (b) neither line (c) the longer line (d) the shorter line
  38. 38.📏 How many kilowatts (kW) is 1800 W? =
  39. 39.🔺 A current of 2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
  40. 40.🔁 In an old-style bulb, which thin wire glows when current flows? (a) the filament (b) the switch (c) the base (d) the glass

Answer key

  1. 4.5
  2. bigger
  3. 1.5
  4. 1100
  5. 3
  6. an output that acts
  7. 15
  8. 4500
  9. True
  10. copper
  11. 1000
  12. slides side to side
  13. 345
  14. a fuse or MCB
  15. 0.5
  16. a complete loop
  17. anode (+)
  18. 12
  19. Yes
  20. True
  21. 1700
  22. run fans in empty rooms
  23. 15
  24. 36
  25. 3000
  26. Yes
  27. 15
  28. 920
  29. P = V × I
  30. set the AC to 24 °C
  31. True
  32. they fix security holes
  33. 15
  34. OFF
  35. a motor
  36. False
  37. the longer line
  38. 1.8
  39. 4
  40. the filament

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