Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 103 · 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.🔍 Which is the odd one out? (a) a button press (b) a soil moisture reading (c) compare with a limit (d) a temperature reading
2. 2.🔺 A current of 3 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
3. 3.🔺 A 10 V supply is joined across a 400 Ω resistor. What current flows (in milliamperes, mA)?
4. 4.🔺 A current of 3 A flows when 12 V is joined across a resistor. What is its resistance (in ohms)?
5. 5.🌐 In an IoT system, which part reads values, decides? (a) microcontroller (b) sensor (c) cloud server (d) phone app
6. 6.✏️ In a cell symbol, which line is the + terminal? (a) both lines (b) neither line (c) the shorter line (d) the longer line
7. 7.Which of these is safe? (a) use mains for a project (b) stop if a part gets hot (c) poke things in a socket (d) use a cable with cuts
8. 8.⚡ Power tells us … (a) the length of a wire (b) the colour of light (c) the size of a cell (d) energy used each second
9. 9.Which of these has no microcontroller inside? (a) a digital alarm clock (b) a washing machine (c) a digital thermometer (d) a bicycle bell
10. 10.🔘 A cell and a bulb are joined to 2 side-by-side paths with one switch on each path — A and B (parallel). A is OFF and B is OFF. Does the bulb glow? (a) Yes (b) No
11. 11.✏️ Why do engineers draw circuits with symbols? (a) symbols are heavier (b) to hide the circuit (c) quick and clear for all (d) to make it colourful
12. 12.Which of these uses electricity? (a) a power station (b) a cell (c) a battery (d) a water pump
13. 13.True or false: to fly kites in open fields is not safe. (a) True (b) False
14. 14.💡 A battery lights 3 identical bulbs joined in parallel. One more identical bulb is added in parallel. How do the bulbs glow now? (a) brighter (b) dimmer (c) the same
15. 15.🔁 count = 3
    repeat 10 times { count = count + 10 }
    What is count at the end?
16. 16.⚡ Which formula gives electric power? (a) P = V × I (b) P = I ÷ V (c) P = V ÷ I (d) P = V + I
17. 17.🔐 Is it a good or a risky habit to log out of shared phones? (a) risky habit (b) good habit
18. 18.🔁 What does a variable do in a program? (a) joins two wires (b) blinks an LED (c) measures light (d) stores a value
19. 19.🔁 count = 4
    while (count < 22) { count = count + 3 }
    How many times does the loop run?
20. 20.💡 An LED (with its resistor) is on pin 8. All pins start LOW. The program runs once:
    set pin 7 LOW
    set pin 7 LOW
    set pin 7 HIGH
    set pin 8 LOW
    Is the LED ON or OFF at the end? (a) ON (b) OFF
21. 21.⏱️ loop forever { LED ON; wait 50 ms; LED OFF; wait 200 ms }
    How many times does the LED blink in 8 seconds?
22. 22.🔍 An object is 323 cm from a distance sensor. Sound travels about 34 cm every millisecond. After how many milliseconds does the echo come back?
23. 23.True or false: “the pump turns on” is the input. (a) True (b) False
24. 24.🔋 Cells joined + to − in a row (series) give … (a) a smaller voltage (b) the same voltage (c) a bigger voltage (d) no voltage
25. 25.💡 Old festival light strings went fully dark when one bulb failed. How were they joined? (a) by Wi-Fi (b) not joined (c) in series (d) in parallel
26. 26.🧾 Which lamp gives the same light for the least power? (a) an oil lamp (b) a filament bulb (c) an LED lamp (d) a candle
27. 27.🌐 A weather station sends one reading every 5 seconds. How many readings does it send in 2 minutes?
28. 28.What does a potentiometer do? (a) beeps for an alarm (b) lets current go one way (c) is a resistance knob (d) limits the current
29. 29.🔺 A current of 0.1 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
30. 30.🌐 Each reading a sensor sends is 20 bytes. How many bytes do 60 readings take?
31. 31.🔍 Which is the odd one out? (a) a steel coin (b) a wooden stick (c) a rubber band (d) a dry cork
32. 32.💡 An LED (with its resistor) is on pin 7. All pins start LOW. The program runs once:
    set pin 7 HIGH
    set pin 8 HIGH
    Is the LED ON or OFF at the end? (a) OFF (b) ON
33. 33.🔁 Is the circuit closed or open if the bulb is unscrewed? (a) closed (b) open
34. 34.🔦 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 steel coin. Does the bulb glow? (a) Yes (b) No
35. 35.True or false: on a cell, “the longer symbol line” means the − (negative) end. (a) False (b) True
36. 36.Which of these mainly makes sound? (a) a room heater (b) a traffic signal (c) an electric kettle (d) a school bell
37. 37.True or false: “many paths for current” is true of a parallel circuit. (a) False (b) True
38. 38.🔺 In the V-I-R triangle, how do we find V? (a) V = I × R (b) V = I ÷ R (c) V = I + R (d) V = R ÷ I
39. 39.🔢 To plan an electronics project, what comes right after “build it with an adult”? (a) pick a problem to solve (b) test it and fix it (c) draw the circuit diagram (d) list inputs and outputs
40. 40.💡 A red LED uses 2 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?

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