Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 756 · 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.⏱️ loop forever { LED ON; wait 150 ms; LED OFF; wait 50 ms }
   How many times does the LED blink in 5 seconds?
2. 2.True or false: if the switch is ON, the circuit is open and no current flows. (a) False (b) True
3. 3.True or false: “used in house wiring” is true of a series circuit. (a) False (b) True
4. 4.🔁 x = 2
   repeat 4 times { x = x × 2 }
   What is x at the end?
5. 5.🔺 A current of 0.1 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
6. 6.🔐 Who should decide which smart devices go in a child’s room? (a) nobody at all (b) a parent or guardian (c) the app’s adverts (d) an online stranger
7. 7.🤖 if (light < 300 AND motion) { porch lamp ON } else { porch lamp OFF }
   The light reading is 350 and motion is not detected (false). What happens? (a) porch lamp OFF (b) porch lamp ON
8. 8.🔺 A current of 3 A flows through a 12 Ω resistor. What is the voltage across it (in volts)? =
9. 9.What does a toggle switch do? (a) springs back when let go (b) flips up or down (c) works only while pressed (d) closes near a magnet
10. 10.What does a toggle switch do? (a) slides side to side (b) closes near a magnet (c) works only while pressed (d) stays where you flip it
11. 11.🔘 A bulb and a cell are joined through 6 switches on 6 side-by-side paths, one switch on each path (parallel). What is the smallest number of switches that must be ON to light the bulb?
12. 12.True or false: “many paths for current” is true of a series circuit. (a) False (b) True
13. 13.Which of these wastes electricity? (a) switch off empty rooms (b) close the fridge quickly (c) unplug idle chargers (d) run fans in empty rooms
14. 14.🔍 An object is 170 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
15. 15.🌐 In an IoT system, which part stores data online? (a) phone app (b) actuator (c) Wi-Fi (d) cloud server
16. 16.🔍 Which is the odd one out? (a) install software updates (b) turn off unused gadgets (c) post your live location (d) read app permissions
17. 17.Which of these usually has a microcontroller inside? (a) a wind-up toy (b) a candle (c) a smart watch (d) a spinning top
18. 18.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V ÷ I (c) R = V + I (d) R = V × I
19. 19.Which of these mainly gives out heat? (a) a siren (b) a rice cooker (c) a doorbell (d) a ceiling fan
20. 20.🔋 On a cell, does “the end with a bump” mean the + end or the − end? (a) − (negative) (b) + (positive)
21. 21.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
22. 22.🔋 How many 3 V cells must be joined in series to give 18 V?
23. 23.🔌 Which part of a screwdriver should an electrician hold? (a) the metal tip (b) the steel shaft (c) the bare end (d) the plastic handle
24. 24.True or false: a tilt switch slides side to side. (a) False (b) True
25. 25.💡 Why is house wiring done in parallel? (a) to save copper only (b) so all go off together (c) to make bulbs dim (d) each gets full voltage
26. 26.🌐 A weather station sends one reading every 30 seconds. How many readings does it send in 1 minute?
27. 27.💡 4 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?
28. 28.🧾 A 250 W appliance runs for 10 hours. How many units (kWh) of electricity does it use? =
29. 29.🔋 7 identical 1.5 V cells are joined in series, but one of them is put in the wrong way round. What is the total voltage now (in volts)? =
30. 30.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) gets bigger (b) becomes zero (c) stays the same (d) gets smaller
31. 31.🔍 Which sensor would you use to switch on with a clap? (a) a distance sensor (b) a motion sensor (c) a sound sensor (d) a rain sensor
32. 32.True or false: a rice cooker mainly makes sound. (a) False (b) True
33. 33.🔁 A bulb has two contacts. How many must be joined into the loop for it to glow? (a) both of them (b) only one (c) it does not matter (d) none
34. 34.💡 On an LED, is the leg by the flat edge the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
35. 35.🔍 Which is the odd one out? (a) leave fridge door open (b) use daylight to read (c) close the fridge quickly (d) set the AC to 24 °C
36. 36.🤖 if (temperature > 36) { show “Hot” } else if (temperature > 20) { show “Warm” } else { show “Cool” }
    The temperature is 18 °C. What is shown? (a) Cool (b) Warm (c) Hot
37. 37.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a candle (c) an LED lamp (d) a filament bulb
38. 38.💡 A red LED uses 2 V and should get 20 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?
39. 39.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) their sum (d) less than either one
40. 40.What does a slide switch do? (a) slides side to side (b) flips up or down (c) closes near a magnet (d) springs back when let go

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