Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 750 · 40 questions

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.

1. 1.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
2. 2.🔁 Is the circuit closed or open if the switch is ON? (a) open (b) closed
3. 3.⚡ What does a school bell mainly change electricity into? (a) light (b) movement (c) heat (d) sound
4. 4.🔐 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
5. 5.🔦 A tester circuit has a new cell, a good bulb and wires with a gap between two clips. We put a wooden stick across the gap. Does the bulb glow? (a) Yes (b) No
6. 6.What does a reed switch do? (a) springs back when let go (b) flips up or down (c) works only while pressed (d) closes near a magnet
7. 7.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
8. 8.🔺 A 9.4 V supply is joined across a 470 Ω resistor. What current flows (in milliamperes, mA)?
9. 9.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
10. 10.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 7 hours. How many watt-hours (Wh) are saved?
11. 11.🔌 Is a small display an input or an output for a microcontroller? (a) output (b) input
12. 12.🌐 In an IoT system, which part stores data online? (a) microcontroller (b) phone app (c) cloud server (d) Wi-Fi
13. 13.⚡ A device works on 24 V and takes 3 A. What is its power (in watts)? =
14. 14.🔋 How many 2 V cells must be joined in series to give 16 V?
15. 15.🔐 A smart-camera app asks for your school name and home address. What should you do? (a) ask a parent first (b) type it all in (c) post it online (d) share it with friends
16. 16.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
17. 17.📶 Digital or analog: a knob turned part way? (a) digital (b) analog
18. 18.🧮 Resistors of 330 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
19. 19.🧩 Which component has coloured bands? (a) fuse (b) potentiometer (c) LDR (d) resistor
20. 20.⚡ A device works on 6 V and takes 3 A. What is its power (in watts)? =
21. 21.🧮 Three equal 15 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
22. 22.True or false: “used in house wiring” is true of a series circuit. (a) False (b) True
23. 23.💡 Old festival light strings went fully dark when one bulb failed. How were they joined? (a) in parallel (b) in series (c) not joined (d) by Wi-Fi
24. 24.🔁 repeat 4 times { repeat 4 times { beep } }
    How many beeps are there?
25. 25.⏱️ repeat 8 times { buzzer ON; wait 200 ms; buzzer OFF; wait 400 ms }
    How many milliseconds does this take in all?
26. 26.🔋 4 identical 2 V cells are joined in series (+ of one cell to − of the next). What is the total voltage (in volts)? =
27. 27.🔦 A circuit has a new cell, a good bulb and a switch that is OFF. All the wires are firmly joined. Does the bulb glow? (a) Yes (b) No
28. 28.🧮 Resistors of 150 Ω, 330 Ω and 100 Ω are joined in series. What is the total resistance (in ohms)?
29. 29.🧩 Which part changes electrical energy into movement? (a) an LED (b) a motor (c) a resistor (d) a fuse
30. 30.Which job needs a buzzer? (a) beep an alarm (b) move water to plants (c) open a gate to 90° (d) show a status light
31. 31.True or false: a cotton thread is a conductor. (a) False (b) True
32. 32.💡 A battery lights 3 identical bulbs joined in series. One more identical bulb is added in series. How do the bulbs glow now? (a) dimmer (b) brighter (c) the same
33. 33.🔌 Is a sound sensor an input or an output for a microcontroller? (a) output (b) input
34. 34.⏱️ How many milliseconds are in 1 second? (a) 10 (b) 60 (c) 100 (d) 1000
35. 35.🔐 Is it a good or a risky habit to tap unknown app links? (a) good habit (b) risky habit
36. 36.True or false: a plastic ruler is an insulator. (a) False (b) True
37. 37.Which of these mainly makes sound? (a) a doorbell (b) a torch (c) a table fan (d) a toaster
38. 38.🔋 Does a power station give electricity or use electricity? (a) gives electricity (b) uses electricity
39. 39.Which of these is measured in amperes (A)? (a) voltage (b) the flow of charge (c) power (d) the push of a cell
40. 40.🔐 A smart speaker is always listening for its wake word. What is a sensible habit? (a) mute it when not in use (b) let strangers use it (c) tell it your passwords (d) put it in the bathroom

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