Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 982 · 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 red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
2. 2.Which of these is the output? (a) a motion sensor signal (b) a button press (c) the pump turns on (d) a temperature reading
3. 3.🔢 To run one loop of a plant-watering program, which comes first: “read the soil sensor” or “wait a few seconds”? (a) wait a few seconds (b) read the soil sensor
4. 4.🔘 Which kind of switch flips up or down? (a) a tilt switch (b) a toggle switch (c) a slide switch (d) a push button
5. 5.True or false: on a cell, “usually the black wire” means the + (positive) end. (a) False (b) True
6. 6.🔁 What does “count = count + 1” do? (a) prints 1 (b) sets count to 1 (c) adds 1 to count (d) takes 1 away
7. 7.⏱️ loop forever { LED ON; wait 100 ms; LED OFF; wait 150 ms }
   How many times does the LED blink in 3 seconds?
8. 8.⚡ Which formula gives electric power? (a) P = V ÷ I (b) P = V + I (c) P = I ÷ V (d) P = V × I
9. 9.🧮 Four equal 40 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
10. 10.🔁 count = 3
    repeat 6 times { count = count + 4 }
    What is count at the end?
11. 11.⚠️ Is it safe to dry your hands first? (a) safe (b) not safe
12. 12.🔢 To get a sensor reading onto a phone, which is the LAST step? (a) it is sent by Wi-Fi (b) the cloud stores it (c) the board reads it (d) the app shows it
13. 13.🧮 A 22 Ω resistor is joined in series with two equal 1000 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
14. 14.🔋 How many 3 V cells must be joined in series to give 24 V?
15. 15.🤖 if (temperature > 30) { fan ON } else { fan OFF }
    The temperature sensor reads 30 °C. What happens? (a) fan OFF (b) fan ON
16. 16.🔺 A 40 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
17. 17.💡 5 identical bulbs are joined in parallel (each on its own side-by-side path) with a battery and a closed switch on the main wire. Bulbs 1 and 2 are taken out of their holders. How many bulbs glow?
18. 18.✏️ In a circuit diagram, which part is drawn as triangle against a bar? (a) ammeter (b) voltmeter (c) junction (d) diode
19. 19.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 50 % (c) 0 % (d) 25 %
20. 20.🧩 Which part changes electrical energy into movement? (a) an LED (b) a resistor (c) a fuse (d) a motor
21. 21.🔺 A current of 25 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
22. 22.💡 Why does an LED need a resistor in series? (a) to store charge (b) to limit the current (c) to change its colour (d) to make it brighter
23. 23.What does the sensor do? (a) shows data to you (b) carries the data (c) acts on a command (d) measures the real world
24. 24.🤖 if (light < 400) { lamp ON } else { lamp OFF }
    The light sensor reads 537. What happens? (a) lamp ON (b) lamp OFF
25. 25.🔍 Which is the odd one out? (a) a fitness band with app (b) a smart energy meter (c) a Wi-Fi smart plug (d) a plain wall switch
26. 26.🤖 Which is a safe power source for a beginner microcontroller board? (a) bare mains wires (b) a 230 V cable (c) USB or a 9 V battery (d) a wall socket directly
27. 27.What does a slide switch do? (a) flips up or down (b) works only while pressed (c) stays where you flip it (d) slides side to side
28. 28.🌐 Is a wind-up clock an IoT device? (a) an IoT device (b) not an IoT device
29. 29.🔺 A current of 50 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🧩 Which component has coloured bands? (a) thermistor (b) transistor (c) buzzer (d) resistor
31. 31.⚡ What does a tube light mainly change electricity into? (a) sound (b) heat (c) light (d) movement
32. 32.🔁 Is the circuit closed or open if the loop is complete? (a) closed (b) open
33. 33.🔺 A current of 40 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
34. 34.⏱️ loop forever { LED ON; wait 250 ms; LED OFF; wait 150 ms }
    How many times does the LED blink in 4 seconds?
35. 35.💡 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
36. 36.🔍 An object is 68 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
37. 37.🔘 What does a switch do in a circuit? (a) opens or closes the loop (b) changes the voltage (c) stores current (d) makes electricity
38. 38.Which of these is safe? (a) throw cells in a fire (b) take cells out after use (c) use a cable with cuts (d) poke things in a socket
39. 39.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the widest gap (d) the gold band
40. 40.🔍 Which is the odd one out? (a) stay away from pylons (b) take cells out after use (c) throw cells in a fire (d) build with an adult near

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