Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 31 · 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.🔐 Privacy for a smart device means controlling … (a) its colour (b) its battery size (c) how loud it beeps (d) who can see your data
2. 2.True or false: a thermistor boosts a small signal. (a) True (b) False
3. 3.💡 6 identical bulbs are joined in series with a battery and a closed switch on the main wire. Bulb 3 is taken out of its holder. How many bulbs glow?
4. 4.🔁 Is the circuit closed or open if a wire has come loose? (a) closed (b) open
5. 5.💡 Why is house wiring done in parallel? (a) so all go off together (b) to make bulbs dim (c) each gets full voltage (d) to save copper only
6. 6.🔋 What is a battery? (a) two or more cells joined (b) a switch with a lid (c) one single wire (d) a kind of bulb
7. 7.🔁 count = 3
   repeat 3 times { count = count + 6 }
   What is count at the end?
8. 8.⚠️ Is it safe to use a cable with cuts? (a) not safe (b) safe
9. 9.🧩 A capacitor in a circuit can … (a) spin a wheel (b) measure heat (c) make light (d) store charge briefly
10. 10.💡 An LED (with its resistor) is on pin 7. All pins start LOW. The program runs once:
    set pin 7 LOW
    set pin 7 HIGH
    Is the LED ON or OFF at the end? (a) OFF (b) ON
11. 11.🤖 if (moisture < 30) { pump ON } else { pump OFF }
    The soil moisture sensor reads 19 %. What happens? (a) pump OFF (b) pump ON
12. 12.🔦 A circuit has a used-up (dead) cell, a good bulb and a switch that is ON. All the wires are firmly joined. A gap in one wire is bridged by a steel spoon. Does the bulb glow? (a) No (b) Yes
13. 13.💡 3 identical bulbs are in parallel and each bulb has its own switch on its path. 2 of the switches are OFF and the rest are ON. How many bulbs glow?
14. 14.💡 A red LED uses 2 V and should get 20 mA. It runs from a 9 V supply. What resistor (in ohms) is needed in series?
15. 15.🔺 A current of 1.5 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
16. 16.True or false: “many values in a range” is a digital signal. (a) True (b) False
17. 17.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 3 V supply. What current flows (in mA)?
18. 18.🔍 Which is the odd one out? (a) a paper calendar (b) a pencil sharpener (c) an app-controlled bulb (d) a plain table fan
19. 19.True or false: to set a strong password is a good habit. (a) True (b) False
20. 20.🔘 Which kind of switch springs back when let go? (a) a reed switch (b) a tilt switch (c) a push button (d) a toggle switch
21. 21.🔋 Does a water pump give electricity or use electricity? (a) gives electricity (b) uses electricity
22. 22.💡 An LED is joined to a 6 V battery with no 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
23. 23.What does a capacitor do? (a) smooths a wobbly supply (b) glows using little power (c) limits the current (d) makes a beeping sound
24. 24.True or false: on a cell, “the shorter symbol line” means the + (positive) end. (a) False (b) True
25. 25.🌐 Each reading a sensor sends is 10 bytes. How many bytes do 20 readings take?
26. 26.🧮 Three equal 150 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
27. 27.🔋 What should you do with used-up cells? (a) bury them in soil (b) give them for recycling (c) throw them in a fire (d) cut them open
28. 28.Which of these is not an IoT device? (a) a fitness band with app (b) a Wi-Fi smart plug (c) a Wi-Fi weather station (d) a battery torch
29. 29.🔁 count = 10
    repeat 8 times { count = count + 2 }
    What is count at the end?
30. 30.📏 How many watts (W) is 0.2 kW?
31. 31.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) cathode (−) (b) anode (+)
32. 32.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
33. 33.✏️ In a circuit diagram, which part is drawn as a circle with A inside? (a) ammeter (b) LED (c) junction (d) capacitor
34. 34.🧾 A family uses 180 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
35. 35.🌈 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
36. 36.⏱️ loop forever { LED ON; wait 250 ms; LED OFF; wait 250 ms }
    How many milliseconds does one blink (ON + OFF) take?
37. 37.True or false: on an LED, the leg by the flat edge is the cathode (−). (a) False (b) True
38. 38.🔁 What must there be for a current to flow? (a) a plastic gap (b) a broken path (c) one loose end (d) a complete loop
39. 39.💡 An LED (with its resistor) is on pin 7. All pins start LOW. The program runs once:
    set pin 8 LOW
    set pin 8 HIGH
    set pin 8 HIGH
    Is the LED ON or OFF at the end? (a) OFF (b) ON
40. 40.🌈 A resistor has the colour bands violet, yellow, yellow. What is its value in kilo-ohms (kΩ)? =

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