Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 787 · 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 blue LED uses 3 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
2. 2.What does a thermistor do? (a) blows if current is high (b) has coloured bands (c) senses how hot it is (d) glows using little power
3. 3.Which of these is a conductor? (a) a plastic straw (b) a ceramic cup (c) a brass key (d) a rubber eraser
4. 4.⏱️ repeat 8 times { buzzer ON; wait 200 ms; buzzer OFF; wait 600 ms }
   How many milliseconds does this take in all?
5. 5.🔍 Which is the odd one out? (a) share camera links (b) read app permissions (c) keep factory passwords (d) tap unknown app links
6. 6.True or false: the flow of charge is measured in watts (W). (a) True (b) False
7. 7.🔘 Two switches are in series. When does the bulb glow? (a) when either is ON (b) never (c) when both are OFF (d) when both are ON
8. 8.🔋 Does a power station give electricity or use electricity? (a) gives electricity (b) uses electricity
9. 9.Which drawing is the symbol for a wire? (a) a straight line (b) two or more cell symbols (c) a small empty box (d) a circle with A inside
10. 10.🔁 What does “count = count + 1” do? (a) takes 1 away (b) prints 1 (c) adds 1 to count (d) sets count to 1
11. 11.💡 An LED is joined to a 5 V battery with no resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) lights up (b) may burn out (c) does not light
12. 12.📶 Digital or analog: how loud a sound is? (a) digital (b) analog
13. 13.Which of these mainly gives out heat? (a) a street light (b) an LED lamp (c) a table fan (d) an electric kettle
14. 14.🔐 Is it a good or a risky habit to ignore update messages? (a) risky habit (b) good habit
15. 15.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) becomes zero (b) stays the same (c) gets smaller (d) gets bigger
16. 16.🔍 Which is the odd one out? (a) a toaster (b) a traffic signal (c) a night lamp (d) an LED lamp
17. 17.🔋 A 3 V battery and two 1.5 V cells are joined in series, all facing the same way. What is the total voltage (in volts)? =
18. 18.True or false: on an LED, the round-side leg is the anode (+). (a) False (b) True
19. 19.🔘 Which kind of switch flips up or down? (a) a tilt switch (b) a push button (c) a toggle switch (d) a reed switch
20. 20.Which of these is a good habit? (a) post your live location (b) ignore update messages (c) set a strong password (d) share the Wi-Fi key
21. 21.🧮 A 3.75 V battery is joined to 12 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
22. 22.⚡ A 3 W device works on 6 V. What current does it take (in amperes)? =
23. 23.🔗 Series or parallel circuit: “a break stops every bulb”? (a) series (b) parallel
24. 24.True or false: on an LED, the shorter leg is the anode (+). (a) True (b) False
25. 25.🤖 Microcontroller or laptop: which one runs many apps at once? (a) microcontroller (b) laptop
26. 26.🗺️ Before building a project, what should you write down first? (a) the box colour (b) nothing at all (c) the final price (d) inputs and outputs
27. 27.Which of these is safe? (a) climb an electric pole (b) use mains for a project (c) stop if a part gets hot (d) touch a switch when wet
28. 28.🔺 A current of 40 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
29. 29.⚡ A 9 W device works on 6 V. What current does it take (in amperes)? =
30. 30.🔍 Which is the odd one out? (a) keep factory passwords (b) post your live location (c) ignore update messages (d) set a strong password
31. 31.🔺 A 4 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
32. 32.🔍 Which is the odd one out? (a) climb an electric pole (b) use small battery cells (c) dry your hands first (d) keep drinks far away
33. 33.🔗 Series or parallel circuit: “one out, the rest glow”? (a) series (b) parallel
34. 34.🔁 total = 0
    for i = 1 to 3 { total = total + i }
    What is total at the end?
35. 35.💡 A battery lights 3 identical bulbs joined in series. One more identical bulb is added in series. How do the bulbs glow now? (a) dimmer (b) the same (c) brighter
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.Which of these mainly gives out light? (a) a traffic signal (b) a siren (c) an exhaust fan (d) a water heater
38. 38.💡 5 identical bulbs are joined in series with a 10 V battery (ideal wires). How many volts does each bulb get? =
39. 39.🔐 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
40. 40.🔁 Is the circuit closed or open if a wire is cut? (a) open (b) closed

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