Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 875 · 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.🔐 Is it a good or a risky habit to keep factory passwords? (a) good habit (b) risky habit
2. 2.🤖 if (light < 300 AND motion) { porch lamp ON } else { porch lamp OFF }
   The light reading is 230 and motion is not detected (false). What happens? (a) porch lamp ON (b) porch lamp OFF
3. 3.⏱️ repeat 7 times { buzzer ON; wait 900 ms; buzzer OFF; wait 100 ms }
   How many milliseconds does this take in all?
4. 4.🧮 A 22 Ω resistor is joined in series with two equal 20 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
5. 5.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
6. 6.🔁 Is the circuit closed or open if the switch is OFF? (a) closed (b) open
7. 7.Which of these saves electricity? (a) leave fridge door open (b) iron one shirt at a time (c) use old filament bulbs (d) switch off empty rooms
8. 8.🔌 Is a plastic straw a conductor or an insulator? (a) an insulator (b) a conductor
9. 9.🔁 count = 9
   repeat 7 times { count = count + 4 }
   What is count at the end?
10. 10.🌐 In an IoT system, which part acts on a command? (a) phone app (b) sensor (c) actuator (d) Wi-Fi
11. 11.What does the phone app do? (a) measures the real world (b) reads values, decides (c) shows data to you (d) carries the data
12. 12.🌈 A resistor has the colour bands white, red, red. What is its value (in ohms)?
13. 13.🔺 A current of 2.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
14. 14.True or false: power is measured in volts (V). (a) True (b) False
15. 15.🔗 Series or parallel circuit: “used in house wiring”? (a) parallel (b) series
16. 16.💡 Does it save or waste electricity to use LED lamps? (a) wastes electricity (b) saves electricity
17. 17.True or false: on an LED, the round-side leg is the cathode (−). (a) False (b) True
18. 18.🔦 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 wooden stick. Does the bulb glow? (a) Yes (b) No
19. 19.True or false: a plain rectangle is the symbol for a resistor. (a) False (b) True
20. 20.Which of these is true of a parallel circuit? (a) a single current path (b) one out, the rest glow (c) bulbs share the voltage (d) one bulb out, all go out
21. 21.🤖 Microcontroller or laptop: which one uses very little power? (a) laptop (b) microcontroller
22. 22.🔺 In the V-I-R triangle, how do we find R? (a) R = V + I (b) R = I ÷ V (c) R = V × I (d) R = V ÷ I
23. 23.True or false: on a cell, “the end with a bump” means the − (negative) end. (a) False (b) True
24. 24.💡 A red LED uses 2 V and should get 10 mA. It runs from a 12 V supply. What resistor (in ohms) is needed in series?
25. 25.🔍 Which is the odd one out? (a) a wooden stick (b) a copper wire (c) a steel spoon (d) a brass key
26. 26.🔘 A cell and a bulb are joined to 3 side-by-side paths with one switch on each path — A, B and C (parallel). A is OFF, B is OFF and C is ON. Does the bulb glow? (a) No (b) Yes
27. 27.🧭 Which part of a microcontroller board shows the board is on? (a) the main chip (b) the USB port (c) the pins (d) the power LED
28. 28.🔋 On a cell, does “the longer symbol line” mean the + end or the − end? (a) − (negative) (b) + (positive)
29. 29.🔍 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?
30. 30.🔺 A current of 0.25 A flows through a 3 Ω resistor. What is the voltage across it (in volts)? =
31. 31.🔺 A 5 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
32. 32.⏱️ loop forever { LED ON; wait 250 ms; LED OFF; wait 950 ms }
    How many milliseconds does one blink (ON + OFF) take?
33. 33.💡 An LED is joined to a 5 V battery through a 220 Ω 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
34. 34.True or false: to fly a kite near wires is not safe. (a) False (b) True
35. 35.Which of these means the circuit is open? (a) the switch is ON (b) a cell is taken out (c) the loop is complete (d) all wires are joined
36. 36.Which of these means the circuit is closed? (a) a cell is taken out (b) the loop is complete (c) the bulb is unscrewed (d) a wire has come loose
37. 37.⏱️ repeat 2 times { buzzer ON; wait 1000 ms; buzzer OFF; wait 700 ms }
    How many milliseconds does this take in all?
38. 38.🌐 A weather station sends one reading every 20 seconds. How many readings does it send in 10 minutes?
39. 39.True or false: a dot where wires meet is the symbol for a junction. (a) False (b) True
40. 40.Which of these means the circuit is closed? (a) the switch is OFF (b) all wires are joined (c) a wire has come loose (d) a wire is cut

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