Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 457 · 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 1.25 V supply is joined across a 5 Ω resistor. What current flows (in amperes)? =
2. 2.True or false: to use LED lamps wastes electricity. (a) True (b) False
3. 3.Which of these saves electricity? (a) iron one shirt at a time (b) set the AC to 24 °C (c) run fans in empty rooms (d) leave fridge door open
4. 4.🔺 A current of 50 mA flows when 20 V is joined across a resistor. What is its resistance (in ohms)?
5. 5.🧮 A 16 V battery is joined to 6 Ω and 10 Ω resistors in series. What current flows (in amperes)? =
6. 6.🤖 if (sound > 60) { red LED ON } else { green LED ON }
   The sound sensor reads 42. What happens? (a) red LED ON (b) green LED ON
7. 7.🔢 To run one loop of a plant-watering program, which is the FIRST step? (a) compare with the limit (b) wait a few seconds (c) read the soil sensor (d) switch the pump on/off
8. 8.🔺 A current of 3 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
9. 9.🔍 Which is the odd one out? (a) a traffic signal (b) a siren (c) a street light (d) a torch
10. 10.True or false: to climb an electric pole is safe. (a) True (b) False
11. 11.Which of these wastes electricity? (a) close the fridge quickly (b) run fans in empty rooms (c) switch off empty rooms (d) use LED lamps
12. 12.True or false: to start a fan when hot, use a light sensor. (a) True (b) False
13. 13.💡 In a series circuit, how many paths does the current have? (a) two (b) none (c) one (d) one for each bulb
14. 14.🤖 if (temperature > 32) { fan ON } else { fan OFF }
    The temperature sensor reads 24 °C. What happens? (a) fan OFF (b) fan ON
15. 15.🔢 To get a sensor reading onto a phone, what comes right after “the sensor measures”? (a) the app shows it (b) the cloud stores it (c) it is sent by Wi-Fi (d) the board reads it
16. 16.🔋 4 identical 1.2 V cells are joined in series (+ of one cell to − of the next). What is the total voltage (in volts)? =
17. 17.🔋 On a cell, does “the end with a bump” mean the + end or the − end? (a) + (positive) (b) − (negative)
18. 18.True or false: “a motion sensor signal” is the input. (a) True (b) False
19. 19.💡 5 identical bulbs are joined in parallel (each on its own side-by-side path) with a battery and a closed switch on the main wire. Bulb 5 is taken out of its holder. How many bulbs glow?
20. 20.✏️ In a cell symbol, which line is the + terminal? (a) the shorter line (b) neither line (c) the longer line (d) both lines
21. 21.Which of these mainly gives out heat? (a) a torch (b) a tube light (c) a water heater (d) a ceiling fan
22. 22.🔋 On a cell, does “the flat end” mean the + end or the − end? (a) + (positive) (b) − (negative)
23. 23.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = I ÷ V (d) P = V + I
24. 24.🔺 A current of 40 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
25. 25.True or false: “a door: open or shut” is a digital signal. (a) True (b) False
26. 26.🔺 A current of 1.5 A flows through a 20 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🔍 Which is the odd one out? (a) change default passwords (b) share camera links (c) post your live location (d) reuse one password
28. 28.🔋 On a cell, does “the longer symbol line” mean the + end or the − end? (a) + (positive) (b) − (negative)
29. 29.🔋 On a cell, does “usually the black wire” mean the + end or the − end? (a) + (positive) (b) − (negative)
30. 30.🧾 A 2000 W appliance runs for 4 hours. How many units (kWh) of electricity does it use? =
31. 31.🔍 Which is the odd one out? (a) a brass key (b) aluminium foil (c) a metal paper clip (d) a rubber eraser
32. 32.🧮 Resistors of 22 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
33. 33.⚡ What does an LED lamp mainly change electricity into? (a) light (b) heat (c) sound (d) movement
34. 34.⚡ A home appliance on the 230 V mains takes 8 A. What is its power (in watts)?
35. 35.⚡ Power tells us … (a) the size of a cell (b) the colour of light (c) the length of a wire (d) energy used each second
36. 36.🔁 What does a variable do in a program? (a) stores a value (b) joins two wires (c) measures light (d) blinks an LED
37. 37.🔺 A 30 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
38. 38.Which of these usually has a microcontroller inside? (a) a digital alarm clock (b) a wind-up toy (c) a plain wall switch (d) a candle
39. 39.Which of these is a conductor? (a) a cotton thread (b) a dry cork (c) a rubber eraser (d) a metal paper clip
40. 40.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?

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