Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 243 · 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.🔢 To get a sensor reading onto a phone, which comes first: “the app shows it” or “the board reads it”? (a) the app shows it (b) the board reads it
2. 2.🌈 A gold fourth band on a resistor means the value may be off by … (a) 25 % (b) 0 % (c) 5 % (d) 50 %
3. 3.🔺 A current of 20 mA flows when 2.4 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.🔁 What must there be for a current to flow? (a) one loose end (b) a broken path (c) a plastic gap (d) a complete loop
5. 5.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
6. 6.🔍 Which is the odd one out? (a) leave the TV on standby (b) use daylight to read (c) set the AC to 24 °C (d) close the fridge quickly
7. 7.Which of these mainly gives out heat? (a) a toaster (b) an exhaust fan (c) a doorbell (d) a buzzer
8. 8.🔐 Is it a good or a risky habit to cover unused cameras? (a) risky habit (b) good habit
9. 9.💡 An LED is joined to a 12 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) does not light (b) may burn out (c) lights up
10. 10.💡 What does LED stand for? (a) light energy dial (b) low energy device (c) large electric dial (d) light-emitting diode
11. 11.🌐 How does a home IoT device usually send its data to the app? (a) by post (b) by shouting (c) through a candle (d) over Wi-Fi
12. 12.🧾 A 500 W appliance runs for 6 hours. How many units (kWh) of electricity does it use? =
13. 13.True or false: to water a dry plant, use a soil moisture sensor. (a) False (b) True
14. 14.Which of these mainly makes movement? (a) a rice cooker (b) an electric drill (c) a street light (d) a buzzer
15. 15.What does a push button do? (a) closes when tipped over (b) stays where you flip it (c) flips up or down (d) works only while pressed
16. 16.🔘 A bulb and a cell are joined through 5 switches one after another in a single loop (series). What is the smallest number of switches that must be ON to light the bulb?
17. 17.⚠️ Is it safe to poke things in a socket? (a) safe (b) not safe
18. 18.💡 Old festival light strings went fully dark when one bulb failed. How were they joined? (a) in parallel (b) not joined (c) by Wi-Fi (d) in series
19. 19.🔁 Is the circuit closed or open if all wires are joined? (a) open (b) closed
20. 20.✏️ In a circuit diagram, which part is drawn as one tall, one short bar? (a) switch (b) resistor (c) motor (d) cell
21. 21.True or false: “a single current path” is true of a parallel circuit. (a) False (b) True
22. 22.🤖 if (light < 200 AND motion) { porch lamp ON } else { porch lamp OFF }
    The light reading is 70 and motion is detected (true). What happens? (a) porch lamp OFF (b) porch lamp ON
23. 23.⚠️ Is it safe to use mains for a project? (a) safe (b) not safe
24. 24.🔺 A 4.8 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
25. 25.What does a thermistor do? (a) glows using little power (b) senses how hot it is (c) stores a little charge (d) blows if current is high
26. 26.🧮 Adding another resistor in series makes the total resistance … (a) bigger (b) zero (c) smaller (d) stay the same
27. 27.🔍 For a microcontroller, is a sensor an input or an output? (a) an output (b) an input (c) a fuse (d) a power source
28. 28.🌈 In the resistor colour code, which number does grey stand for?
29. 29.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
30. 30.True or false: on a cell, “usually the black wire” means the + (positive) end. (a) False (b) True
31. 31.⏱️ What does “wait 500 ms” do? (a) turns the LED off (b) pauses for half a second (c) waits 500 seconds (d) blinks 500 times
32. 32.🔋 A 6 V battery and one 1.5 V cell are joined in series, all facing the same way. What is the total voltage (in volts)? =
33. 33.🔍 Which is the odd one out? (a) keep factory passwords (b) tap unknown app links (c) reuse one password (d) set a strong password
34. 34.Which job needs a display? (a) show a status light (b) show the temperature (c) spin a robot’s wheels (d) beep an alarm
35. 35.🧩 A capacitor in a circuit can … (a) spin a wheel (b) store charge briefly (c) measure heat (d) make light
36. 36.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I × R (d) V = I ÷ R
37. 37.🔺 A current of 20 mA flows when 2 V is joined across a resistor. What is its resistance (in ohms)?
38. 38.🤖 “if (A AND B)” is true when … (a) both are false (b) only B is true (c) both A and B are true (d) only A is true
39. 39.✏️ In a cell symbol, which line is the + terminal? (a) the shorter line (b) the longer line (c) both lines (d) neither line
40. 40.🤖 if (moisture < 30) { pump ON } else { pump OFF }
    The soil moisture sensor reads 25 %. What happens? (a) pump OFF (b) pump ON

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