Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 320 · 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.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 20 Ω resistor? (a) red-black-black (b) orange-black-black (c) orange-red-black (d) red-black-brown
2. 2.🌐 Is a wind-up clock an IoT device? (a) an IoT device (b) not an IoT device
3. 3.🔢 To get a sensor reading onto a phone, which is the FIRST step? (a) it is sent by Wi-Fi (b) the board reads it (c) the app shows it (d) the sensor measures
4. 4.What does a tilt switch do? (a) slides side to side (b) flips up or down (c) closes when tipped over (d) closes near a magnet
5. 5.True or false: to set the AC to 24 °C wastes electricity. (a) True (b) False
6. 6.🧾 A family uses 100 units of electricity in a month and each unit costs ₹4. What is the bill (in ₹)?
7. 7.⚙️ Which actuator would you use to move water to plants? (a) a buzzer (b) a servo motor (c) a pump (d) an LED
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.💡 Does it save or waste electricity to close the fridge quickly? (a) wastes electricity (b) saves electricity
10. 10.🔢 To run one loop of a plant-watering program, which comes first: “wait a few seconds” or “read the soil sensor”? (a) read the soil sensor (b) wait a few seconds
11. 11.🔍 A distance sensor sends a sound pulse and hears the echo 14 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
12. 12.Which of these means the circuit is open? (a) the loop is complete (b) all wires are joined (c) the switch is ON (d) a wire is cut
13. 13.🤖 if (sound > 60) { red LED ON } else { green LED ON }
    The sound sensor reads 42. What happens? (a) green LED ON (b) red LED ON
14. 14.🔁 A bulb has two contacts. How many must be joined into the loop for it to glow? (a) none (b) it does not matter (c) only one (d) both of them
15. 15.🧮 A 220 Ω resistor is joined in series with two equal 50 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
16. 16.True or false: a laptop uses very little power. (a) False (b) True
17. 17.What does a toggle switch do? (a) flips up or down (b) works only while pressed (c) closes when tipped over (d) slides side to side
18. 18.⏱️ repeat 8 times { buzzer ON; wait 500 ms; buzzer OFF; wait 900 ms }
    How many milliseconds does this take in all?
19. 19.True or false: “a button: pressed or not” is an analog signal. (a) True (b) False
20. 20.🔺 A current of 0.25 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
21. 21.🧾 A 500 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
22. 22.🧮 A 4.4 V battery is joined to 12 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
23. 23.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 1600 Ω resistor? (a) brown-blue-brown (b) blue-brown-red (c) brown-blue-orange (d) brown-blue-red
24. 24.🔋 5 identical 2 V cells are joined side by side in parallel (all + ends together, all − ends together). What is the voltage across them (in volts)? =
25. 25.💡 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?
26. 26.⚡ What does a ceiling fan mainly change electricity into? (a) sound (b) heat (c) movement (d) light
27. 27.Which of these mainly gives out light? (a) a torch (b) a school bell (c) a doorbell (d) a table fan
28. 28.Which of these is the input? (a) count button presses (b) the pump turns on (c) a buzzer beeps (d) a motion sensor signal
29. 29.True or false: “the room temperature” is a digital signal. (a) False (b) True
30. 30.💡 An LED (with its resistor) is on pin 7. All pins start LOW. The program runs once:
    set pin 8 LOW
    set pin 8 LOW
    set pin 7 LOW
    set pin 7 HIGH
    Is the LED ON or OFF at the end? (a) OFF (b) ON
31. 31.Which of these means the circuit is closed? (a) a cell is taken out (b) a wire has come loose (c) a wire is cut (d) the switch is ON
32. 32.⚠️ Is it safe to poke things in a socket? (a) safe (b) not safe
33. 33.🔁 count = 3
    while (count < 15) { count = count + 3 }
    How many times does the loop run?
34. 34.Which of these uses electricity? (a) a cell (b) a battery (c) an air conditioner (d) a solar panel
35. 35.🤖 Microcontroller or laptop: which one needs much more power? (a) microcontroller (b) laptop
36. 36.True or false: on a cell, “the shorter symbol line” means the + (positive) end. (a) False (b) True
37. 37.Which of these is an output? (a) a sound sensor (b) a light sensor (c) a turning knob (d) a motor
38. 38.🌈 A resistor has the colour bands yellow, orange, red. What is its value in kilo-ohms (kΩ)? =
39. 39.💡 An LED is joined to a 6 V battery through a 330 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
40. 40.🌐 Is a smart energy meter an IoT device? (a) not an IoT device (b) an IoT device

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