Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 781 · 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 does an LED need a resistor in series? (a) to make it brighter (b) to change its colour (c) to limit the current (d) to store charge
2. 2.True or false: if a cell is taken out, the circuit is closed and current flows. (a) True (b) False
3. 3.🔦 A circuit has a new 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 safety pin. Does the bulb glow? (a) Yes (b) No
4. 4.Which of these is true of a parallel circuit? (a) many paths for current (b) one bulb out, all go out (c) bulbs share the voltage (d) a single current path
5. 5.Which of these is a good habit? (a) post your live location (b) keep factory passwords (c) tap unknown app links (d) change default passwords
6. 6.🔺 A current of 40 mA flows when 4.8 V is joined across a resistor. What is its resistance (in ohms)?
7. 7.Which of these is a conductor? (a) a rubber band (b) a woollen thread (c) a safety pin (d) a plastic ruler
8. 8.True or false: an LED turns a fan or wheels. (a) False (b) True
9. 9.💡 A battery lights 5 identical bulbs joined in series. One more identical bulb is added in series. How do the bulbs glow now? (a) the same (b) brighter (c) dimmer
10. 10.True or false: if a wire has come loose, the circuit is open and no current flows. (a) False (b) True
11. 11.🔍 Which sensor would you use to switch on lamps at dusk? (a) a sound sensor (b) a motion sensor (c) a light sensor (d) a temperature sensor
12. 12.💡 Does it save or waste electricity to leave the TV on standby? (a) saves electricity (b) wastes electricity
13. 13.🔋 How many 1.2 V cells must be joined in series to give 9.6 V?
14. 14.True or false: a capacitor senses how bright it is. (a) False (b) True
15. 15.True or false: on an LED, the leg by the flat edge is the anode (+). (a) True (b) False
16. 16.True or false: “a single current path” is true of a parallel circuit. (a) False (b) True
17. 17.🧮 A 1.4 V battery is joined to 12 Ω and 2 Ω resistors in series. What current flows (in amperes)? =
18. 18.Which of these is safe? (a) touch a fallen wire (b) fly a kite near wires (c) open a phone charger (d) dry your hands first
19. 19.🔍 Which is the odd one out? (a) open a phone charger (b) throw cells in a fire (c) build with an adult near (d) poke things in a socket
20. 20.Which of these is not an IoT device? (a) a Wi-Fi smart plug (b) an app-controlled bulb (c) a battery torch (d) a fitness band with app
21. 21.🔺 A 6 V supply is joined across a 12 Ω resistor. What current flows (in amperes)? =
22. 22.Which of these wastes electricity? (a) set the AC to 24 °C (b) iron one shirt at a time (c) use daylight to read (d) use LED lamps
23. 23.🧭 Which part of a microcontroller board keeps the voltage steady? (a) the pins (b) the USB port (c) the power LED (d) the voltage regulator
24. 24.What does a toggle switch do? (a) closes when tipped over (b) closes near a magnet (c) springs back when let go (d) stays where you flip it
25. 25.📏 Voltmeter or ammeter: which one is joined across a part? (a) ammeter (b) voltmeter
26. 26.🔁 total = 0
    for i = 1 to 4 { total = total + i }
    What is total at the end?
27. 27.Which job is done by the reset button? (a) connect sensors and LEDs (b) keeps the voltage steady (c) runs the program (d) restarts the program
28. 28.True or false: a reed switch flips up or down. (a) False (b) True
29. 29.True or false: a thermistor makes a beeping sound. (a) True (b) False
30. 30.Which of these mainly gives out heat? (a) a ceiling fan (b) a mixer grinder (c) an electric iron (d) a buzzer
31. 31.🔍 Which is the odd one out? (a) a tube light (b) a room heater (c) a torch (d) a traffic signal
32. 32.💡 6 identical bulbs are joined in series with a battery and a closed switch on the main wire. Bulb 1 is taken out of its holder. How many bulbs glow?
33. 33.🔋 3 identical 2 V cells are joined in series (+ of one cell to − of the next). What is the total voltage (in volts)? =
34. 34.🔐 Is it a good or a risky habit to share the Wi-Fi key? (a) good habit (b) risky habit
35. 35.Which of these is a conductor? (a) a cotton thread (b) a dry cork (c) aluminium foil (d) a paper strip
36. 36.💡 2 identical bulbs are joined in parallel across a 9 V battery (ideal wires). How many volts does each bulb get? =
37. 37.✏️ In a circuit diagram, which part is drawn as triangle against a bar? (a) cell (b) capacitor (c) motor (d) diode
38. 38.📶 On a 5 V board, a pin set HIGH gives about … (a) 5 V (b) 0 V (c) 230 V (d) 50 V
39. 39.🔢 To plan an electronics project, what comes right after “list inputs and outputs”? (a) test it and fix it (b) build it with an adult (c) pick a problem to solve (d) draw the circuit diagram
40. 40.🔺 A 6 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?

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