Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 380 · 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 of these means the circuit is closed? (a) the switch is ON (b) a wire is cut (c) a cell is taken out (d) a wire has come loose
2. 2.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 6 V supply. What current flows (in mA)?
3. 3.🔁 count = 0
   while (count < 15) { count = count + 5 }
   How many times does the loop run?
4. 4.🔁 Is the circuit closed or open if a wire has come loose? (a) open (b) closed
5. 5.📏 Voltmeter or ammeter: which one is joined in series? (a) voltmeter (b) ammeter
6. 6.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) more than either one (d) their sum
7. 7.🤖 Microcontroller or laptop: which one uses very little power? (a) microcontroller (b) laptop
8. 8.⚡ A home appliance on the 230 V mains takes 2 A. What is its power (in watts)?
9. 9.💡 In a parallel circuit, one bulb breaks. What happens to the others? (a) they explode (b) they get dimmer (c) they all go out (d) they keep glowing
10. 10.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water tank lid (c) the pipe colour (d) the water pressure
11. 11.🔍 A distance sensor sends a sound pulse and hears the echo 15 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
12. 12.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
13. 13.Which of these mainly makes movement? (a) a street light (b) an LED lamp (c) an electric toy car (d) a traffic signal
14. 14.🔐 A smart speaker is always listening for its wake word. What is a sensible habit? (a) mute it when not in use (b) put it in the bathroom (c) tell it your passwords (d) let strangers use it
15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets smaller (b) becomes zero (c) gets bigger (d) stays the same
16. 16.🔍 Which is the odd one out? (a) a temperature reading (b) compare with a limit (c) a button press (d) a motion sensor signal
17. 17.🔗 Series or parallel circuit: “one bulb out, all go out”? (a) series (b) parallel
18. 18.💡 An LED is joined to a 5 V battery through a 220 Ω resistor; the leg next to the flat edge of its rim goes to the + side. What happens? (a) may burn out (b) does not light (c) lights up
19. 19.🔍 Which is the odd one out? (a) keep factory passwords (b) post your live location (c) share camera links (d) set up with a parent
20. 20.🔐 Why install updates on IoT devices? (a) they delete the Wi-Fi (b) they make it heavier (c) they fix security holes (d) they change the colour
21. 21.💡 An LED (with its resistor) is on pin 8. All pins start LOW. The program runs once:
    set pin 7 LOW
    set pin 7 LOW
    set pin 8 HIGH
    set pin 7 LOW
    set pin 7 HIGH
    Is the LED ON or OFF at the end? (a) ON (b) OFF
22. 22.Which of these is an input? (a) a water pump (b) a speaker (c) a buzzer (d) a light sensor
23. 23.Which of these is a risky habit? (a) keep factory passwords (b) install software updates (c) turn off unused gadgets (d) share only needed data
24. 24.Which of these is a conductor? (a) a plastic ruler (b) a woollen thread (c) a steel coin (d) a rubber eraser
25. 25.💡 A red LED (it uses 2 V) is joined with a 150 Ω resistor to a 2.75 V supply. What current flows (in mA)?
26. 26.🧩 Which component stores a little charge? (a) transistor (b) capacitor (c) resistor (d) buzzer
27. 27.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 0 % (c) 5 % (d) 25 %
28. 28.🔁 Is the circuit closed or open if a cell is taken out? (a) closed (b) open
29. 29.🔺 A current of 2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🗺️ Before building a project, what should you write down first? (a) the box colour (b) inputs and outputs (c) the final price (d) nothing at all
31. 31.🧩 Which component makes things spin? (a) LED (b) fuse (c) buzzer (d) motor
32. 32.🌈 A resistor has the colour bands brown, grey, red. What is its value (in ohms)?
33. 33.🌐 How does a home IoT device usually send its data to the app? (a) through a candle (b) over Wi-Fi (c) by post (d) by shouting
34. 34.🔺 A current of 2.5 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
35. 35.True or false: if the loop is complete, the circuit is closed and current flows. (a) False (b) True
36. 36.True or false: to water a dry plant, use a soil moisture sensor. (a) True (b) False
37. 37.⏱️ A program says “wait 2750 ms”. How many seconds is that? =
38. 38.True or false: a line lifted at a gap is the symbol for a switch. (a) False (b) True
39. 39.Which of these is true of a parallel circuit? (a) bulbs share the voltage (b) a single current path (c) used in house wiring (d) a break stops every bulb
40. 40.🧩 Which component is a resistance knob? (a) capacitor (b) LED (c) transistor (d) potentiometer

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