Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 451 · 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 2 V supply is joined across a 100 Ω resistor. What current flows (in milliamperes, mA)?
2. 2.⚡ What does a school bell mainly change electricity into? (a) sound (b) light (c) movement (d) heat
3. 3.⚠️ Is it safe to dry your hands first? (a) safe (b) not safe
4. 4.🔺 A current of 20 mA flows through a 150 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🗺️ Before building a project, what should you write down first? (a) the box colour (b) inputs and outputs (c) nothing at all (d) the final price
6. 6.Which of these is a conductor? (a) a plastic ruler (b) a rubber band (c) a steel spoon (d) a paper strip
7. 7.⚡ A device works on 24 V and takes 0.25 A. What is its power (in watts)? =
8. 8.💡 An LED is joined to a 6 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
9. 9.True or false: a slide switch slides side to side. (a) False (b) True
10. 10.True or false: on a cell, “the end with a bump” means the − (negative) end. (a) False (b) True
11. 11.🤖 In “if (temp > 30)”, what runs when temp is exactly 30? (a) both parts (b) neither part (c) the if part (d) the else part
12. 12.💡 Old festival light strings went fully dark when one bulb failed. How were they joined? (a) in parallel (b) in series (c) by Wi-Fi (d) not joined
13. 13.💡 Why does an LED need a resistor in series? (a) to limit the current (b) to change its colour (c) to make it brighter (d) to store charge
14. 14.🌐 A weather station sends one reading every 20 seconds. How many readings does it send in 10 minutes?
15. 15.✏️ In a circuit diagram, wires are usually drawn as … (a) straight lines (b) little stars (c) dotted circles (d) wavy lines
16. 16.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the gold band (d) the widest gap
17. 17.True or false: a resistor lets current go one way. (a) False (b) True
18. 18.🔁 x = 3
    repeat 4 times { x = x × 2 }
    What is x at the end?
19. 19.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
20. 20.🧩 Which part changes electrical energy into sound? (a) a buzzer (b) a diode (c) a resistor (d) a capacitor
21. 21.🔍 Which is the odd one out? (a) leave fridge door open (b) switch off empty rooms (c) leave the TV on standby (d) use old filament bulbs
22. 22.🧮 Resistors of 22 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
23. 23.True or false: power is measured in volts (V). (a) False (b) True
24. 24.🔘 Which kind of switch springs back when let go? (a) a push button (b) a slide switch (c) a reed switch (d) a tilt switch
25. 25.True or false: on a cell, “usually the black wire” means the − (negative) end. (a) False (b) True
26. 26.🌈 In the resistor colour code, which number does red stand for?
27. 27.🔍 Which is the odd one out? (a) a smart energy meter (b) a Wi-Fi smart plug (c) an app-controlled bulb (d) a battery torch
28. 28.📏 How many watts (W) is 1.5 kW?
29. 29.🔘 Switch A is on the main wire next to the cell and the bulb; then the wire splits into two side-by-side paths, one with switch B and one with switch C. A is OFF, B is OFF and C is ON. Does the bulb glow? (a) Yes (b) No
30. 30.Which of these wastes electricity? (a) run fans in empty rooms (b) unplug idle chargers (c) use daylight to read (d) close the fridge quickly
31. 31.⏱️ How many milliseconds is a wait of 0.5 seconds?
32. 32.🤖 if (light < 200 AND motion) { porch lamp ON } else { porch lamp OFF }
    The light reading is 330 and motion is detected (true). What happens? (a) porch lamp ON (b) porch lamp OFF
33. 33.✏️ In a cell symbol, which line is the + terminal? (a) the shorter line (b) the longer line (c) neither line (d) both lines
34. 34.True or false: on a cell, “the end with a bump” means the + (positive) end. (a) False (b) True
35. 35.🧾 A family uses 150 units of electricity in a month and each unit costs ₹5. What is the bill (in ₹)?
36. 36.⚠️ Who should be with you when you build a circuit? (a) nobody (b) a stranger online (c) a trusted adult (d) a younger child
37. 37.🔋 How many volts does one ordinary torch cell give? (a) 0.5 V (b) 1.5 V (c) 15 V (d) 230 V
38. 38.Which of these gives us electricity? (a) a television (b) a cell (c) a mobile phone (d) a washing machine
39. 39.🗺️ In an input → process → output plan, is “a button press” the input, the process or the output? (a) process (b) output (c) input
40. 40.🧩 Which component blows if current is high? (a) LDR (b) fuse (c) buzzer (d) LED

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