Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 5 · 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.💡 Why is house wiring done in parallel? (a) so all go off together (b) to save copper only (c) to make bulbs dim (d) each gets full voltage
2. 2.🔋 On a cell, does “the flat end” mean the + end or the − end? (a) − (negative) (b) + (positive)
3. 3.🌈 A gold fourth band on a resistor means the value may be off by … (a) 50 % (b) 5 % (c) 0 % (d) 25 %
4. 4.🧮 Resistors of 10 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
5. 5.🤖 if (moisture < 40) { pump ON } else { pump OFF }
   The soil moisture sensor reads 27 %. What happens? (a) pump ON (b) pump OFF
6. 6.What does a tilt switch do? (a) closes near a magnet (b) closes when tipped over (c) slides side to side (d) springs back when let go
7. 7.🔍 Which is the odd one out? (a) reuse one password (b) install software updates (c) change default passwords (d) cover unused cameras
8. 8.🧾 A 75 W filament bulb is swapped for a 12 W LED lamp that gives about the same light. Both would run for 6 hours. How many watt-hours (Wh) are saved?
9. 9.True or false: on a cell, “the flat end” means the − (negative) end. (a) True (b) False
10. 10.🌈 A resistor has the colour bands yellow, brown, red. What is its value in kilo-ohms (kΩ)? =
11. 11.🔺 A current of 0.2 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
12. 12.⏱️ How many milliseconds is a wait of 0.4 seconds?
13. 13.⏱️ loop forever { LED ON; wait 250 ms; LED OFF; wait 150 ms }
    How many times does the LED blink in 12 seconds?
14. 14.🤖 if (temperature > 30) { show “Hot” } else if (temperature > 25) { show “Warm” } else { show “Cool” }
    The temperature is 31 °C. What is shown? (a) Warm (b) Hot (c) Cool
15. 15.🔁 What does a variable do in a program? (a) measures light (b) joins two wires (c) blinks an LED (d) stores a value
16. 16.💡 An LED is joined to a 5 V battery with no resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
17. 17.🔍 Which is the odd one out? (a) a copper wire (b) a safety pin (c) a paper strip (d) a steel spoon
18. 18.True or false: “an alert on the phone” is the process. (a) False (b) True
19. 19.🔦 A circuit has a new cell, a good bulb and a switch that is OFF. All the wires are firmly joined. A gap in one wire is bridged by a graphite rod. Does the bulb glow? (a) Yes (b) No
20. 20.True or false: if all wires are joined, the circuit is open and no current flows. (a) True (b) False
21. 21.🔦 A tester circuit has a new cell, a good bulb and wires with a gap between two clips. We put a copper wire across the gap. Does the bulb glow? (a) No (b) Yes
22. 22.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
23. 23.🔍 Which is the odd one out? (a) a push button (b) a small display (c) a motor (d) an LED
24. 24.🧩 Which component senses how hot it is? (a) motor (b) resistor (c) thermistor (d) buzzer
25. 25.🔢 To run one loop of a plant-watering program, which is the FIRST step? (a) wait a few seconds (b) read the soil sensor (c) compare with the limit (d) switch the pump on/off
26. 26.🔍 Which is the odd one out? (a) close the fridge quickly (b) use LED lamps (c) use old filament bulbs (d) unplug idle chargers
27. 27.💡 Old festival light strings went fully dark when one bulb failed. How were they joined? (a) not joined (b) in parallel (c) by Wi-Fi (d) in series
28. 28.💡 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) does not light (b) may burn out (c) lights up
29. 29.True or false: to poke things in a socket is not safe. (a) True (b) False
30. 30.Which of these is not safe? (a) fly a kite near wires (b) dry your hands first (c) build with an adult near (d) stay away from pylons
31. 31.🏠 Which is a smart-home example? (a) a candle in a jar (b) lights on from an app (c) a hand fan (d) a printed map
32. 32.💡 In a parallel circuit, one bulb breaks. What happens to the others? (a) they explode (b) they keep glowing (c) they all go out (d) they get dimmer
33. 33.🔍 Which is the odd one out? (a) a small display (b) a sound sensor (c) a light sensor (d) a push button
34. 34.🔋 How many 1.2 V cells must be joined in series to give 3.6 V?
35. 35.Which of these is an IoT device? (a) a Wi-Fi doorbell camera (b) a battery torch (c) a paper calendar (d) a pencil sharpener
36. 36.⚡ A device works on 12 V and takes 0.2 A. What is its power (in watts)? =
37. 37.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
38. 38.🔁 A bulb has two contacts. How many must be joined into the loop for it to glow? (a) only one (b) none (c) it does not matter (d) both of them
39. 39.🤖 if (temperature > 35) { show “Hot” } else if (temperature > 25) { show “Warm” } else { show “Cool” }
    The temperature is 19 °C. What is shown? (a) Cool (b) Hot (c) Warm
40. 40.🔁 repeat 2 times { repeat 3 times { beep } }
    How many beeps are there?

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