Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 87 · 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.⏱️ loop forever { LED ON; wait 800 ms; LED OFF; wait 600 ms }
   How many milliseconds does one blink (ON + OFF) take?
2. 2.🔘 When a switch is ON, the circuit is … (a) closed (b) broken (c) open (d) cut
3. 3.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.💡 Old festival light strings went fully dark when one bulb failed. How were they joined? (a) in parallel (b) not joined (c) in series (d) by Wi-Fi
5. 5.True or false: to dry your hands first is safe. (a) True (b) False
6. 6.🤖 if (temperature > 37) { show “Hot” } else if (temperature > 25) { show “Warm” } else { show “Cool” }
   The temperature is 12 °C. What is shown? (a) Warm (b) Hot (c) Cool
7. 7.🔍 Which is the odd one out? (a) use mains for a project (b) open a phone charger (c) stay away from pylons (d) throw cells in a fire
8. 8.⏱️ How many milliseconds is a wait of 2 seconds?
9. 9.🤖 if (temperature > 25) { fan ON } else { fan OFF }
   The temperature sensor reads 25 °C. What happens? (a) fan ON (b) fan OFF
10. 10.🔌 Is a wooden stick a conductor or an insulator? (a) a conductor (b) an insulator
11. 11.🔍 Which is the odd one out? (a) the fan starts (b) decide if soil is dry (c) an alert on the phone (d) a buzzer beeps
12. 12.Which job needs a servo motor? (a) spin a robot’s wheels (b) show a status light (c) beep an alarm (d) open a gate to 90°
13. 13.💡 An LED (with its resistor) is on pin 8. All pins start LOW. The program runs once:
    set pin 7 LOW
    set pin 7 HIGH
    set pin 8 LOW
    Is the LED ON or OFF at the end? (a) OFF (b) ON
14. 14.🌐 In an IoT system, which part measures the real world? (a) Wi-Fi (b) microcontroller (c) cloud server (d) sensor
15. 15.🔺 A current of 25 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
16. 16.⚡ Which tiny particles drift along a metal wire to carry the current? (a) dust particles (b) photons (c) water drops (d) electrons
17. 17.💡 A battery lights 2 identical bulbs joined in series. One more identical bulb is added in series. How do the bulbs glow now? (a) the same (b) dimmer (c) brighter
18. 18.🤖 In “if (temp > 30)”, what runs when temp is exactly 30? (a) neither part (b) the if part (c) both parts (d) the else part
19. 19.🧮 A 4 V battery is joined to 5 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
20. 20.Which job needs a motion sensor? (a) spot someone walking in (b) close a window in rain (c) make a parking alarm (d) open blinds at sunrise
21. 21.🔋 2 identical 3 V cells are joined side by side in parallel (all + ends together, all − ends together). What is the voltage across them (in volts)? =
22. 22.Which of these is an insulator? (a) a graphite rod (b) a glass marble (c) a copper wire (d) a steel coin
23. 23.🧩 Which part changes electrical energy into movement? (a) a fuse (b) a motor (c) a resistor (d) an LED
24. 24.True or false: on an LED, the shorter leg is the cathode (−). (a) False (b) True
25. 25.True or false: to set the AC to 24 °C wastes electricity. (a) True (b) False
26. 26.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) any band (d) the one nearest an end
27. 27.Which of these saves electricity? (a) use old filament bulbs (b) leave fridge door open (c) set the AC to 24 °C (d) iron one shirt at a time
28. 28.⏱️ A program says “wait 5000 ms”. How many seconds is that? =
29. 29.🔺 A 4 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
30. 30.True or false: the ammeter is joined across a part. (a) True (b) False
31. 31.🧮 Resistors of 10 Ω, 330 Ω and 20 Ω are joined in series. What is the total resistance (in ohms)?
32. 32.⏱️ How many milliseconds is a wait of 2.1 seconds?
33. 33.⚡ A solar panel changes which kind of energy into electricity? (a) sound energy (b) chemical energy (c) wind energy (d) light energy
34. 34.⚡ Power tells us … (a) the length of a wire (b) energy used each second (c) the size of a cell (d) the colour of light
35. 35.✏️ In a cell symbol, which line is the + terminal? (a) the shorter line (b) neither line (c) the longer line (d) both lines
36. 36.🔁 x = 1
    repeat 5 times { x = x × 2 }
    What is x at the end?
37. 37.Which of these gives us electricity? (a) an air conditioner (b) a mobile phone (c) a washing machine (d) a bicycle dynamo
38. 38.💡 3 identical bulbs are in parallel and each bulb has its own switch on its path. 1 of the switches is OFF and the rest are ON. How many bulbs glow?
39. 39.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) True (b) False
40. 40.⏱️ How many milliseconds are in 1 second? (a) 100 (b) 60 (c) 10 (d) 1000

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