Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 889 · 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.🔁 repeat 6 times { repeat 5 times { beep } }
   How many beeps are there?
2. 2.🔺 A 6 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
3. 3.🔁 repeat 5 times { repeat 2 times { beep } }
   How many beeps are there?
4. 4.🤖 if (distance < 15) { buzzer beeps } else { buzzer is silent }
   The distance sensor reads 16 cm. What happens? (a) buzzer beeps (b) buzzer is silent
5. 5.🔋 What is a battery? (a) two or more cells joined (b) one single wire (c) a switch with a lid (d) a kind of bulb
6. 6.What does a push button do? (a) slides side to side (b) closes near a magnet (c) springs back when let go (d) closes when tipped over
7. 7.🔦 A circuit has a used-up (dead) 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
8. 8.True or false: a buzzer beeps for an alarm. (a) False (b) True
9. 9.⏱️ How many milliseconds is a wait of 1.4 seconds?
10. 10.What does the microcontroller do? (a) acts on a command (b) stores data online (c) measures the real world (d) reads values, decides
11. 11.⚠️ Why must we never touch switches with wet hands? (a) it spoils the paint (b) it is just untidy (c) water carries current (d) water makes it cold
12. 12.True or false: to fly kites in open fields is safe. (a) False (b) True
13. 13.🔌 Which part of a screwdriver should an electrician hold? (a) the bare end (b) the steel shaft (c) the plastic handle (d) the metal tip
14. 14.💡 Old festival light strings went fully dark when one bulb failed. How were they joined? (a) in parallel (b) by Wi-Fi (c) in series (d) not joined
15. 15.🤖 When the main loop of a microcontroller program ends, what happens? (a) it starts again (b) the board breaks (c) it stops forever (d) it deletes itself
16. 16.⏱️ loop forever { LED ON; wait 100 ms; LED OFF; wait 450 ms }
    How many milliseconds does one blink (ON + OFF) take?
17. 17.⚡ Power tells us … (a) energy used each second (b) the length of a wire (c) the colour of light (d) the size of a cell
18. 18.🔺 A current of 0.25 A flows when 5 V is joined across a resistor. What is its resistance (in ohms)?
19. 19.💡 3 identical bulbs are joined in parallel (each on its own side-by-side path) with a battery and a closed switch on the main wire. Bulbs 1 and 3 are taken out of their holders. How many bulbs glow?
20. 20.🔢 To get a sensor reading onto a phone, what comes right after “the sensor measures”? (a) the app shows it (b) it is sent by Wi-Fi (c) the board reads it (d) the cloud stores it
21. 21.🔍 Which is the odd one out? (a) count button presses (b) compare with a limit (c) a motion sensor signal (d) check if temp > 30
22. 22.🔍 Which is the odd one out? (a) a plain table fan (b) a smart energy meter (c) a wind-up clock (d) a plain wall switch
23. 23.🧮 A 220 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)?
24. 24.🤖 if (sound > 60) { red LED ON } else { green LED ON }
    The sound sensor reads 50. What happens? (a) red LED ON (b) green LED ON
25. 25.🔍 Which sensor would you use to switch on with a clap? (a) a rain sensor (b) a soil moisture sensor (c) a light sensor (d) a sound sensor
26. 26.🌈 A resistor has the colour bands white, green, yellow. What is its value in kilo-ohms (kΩ)? =
27. 27.🔋 On a cell, does “usually the black wire” mean the + end or the − end? (a) + (positive) (b) − (negative)
28. 28.Which of these is true of a parallel circuit? (a) one bulb out, all go out (b) a break stops every bulb (c) each gets the full volts (d) a single current path
29. 29.📏 Voltmeter or ammeter: which one measures voltage? (a) ammeter (b) voltmeter
30. 30.Which of these is a risky habit? (a) set a strong password (b) reuse one password (c) log out of shared phones (d) install software updates
31. 31.🔺 A current of 50 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
32. 32.True or false: if a cell is taken out, the circuit is open and no current flows. (a) True (b) False
33. 33.Which of these wastes electricity? (a) use daylight to read (b) close the fridge quickly (c) unplug idle chargers (d) iron one shirt at a time
34. 34.🧮 Resistors of 150 Ω, 150 Ω, 68 Ω and 10 Ω are joined in series. What is the total resistance (in ohms)?
35. 35.🌈 A resistor has the colour bands red, yellow, yellow. What is its value in kilo-ohms (kΩ)? =
36. 36.🔁 What must there be for a current to flow? (a) a complete loop (b) a broken path (c) a plastic gap (d) one loose end
37. 37.🔐 Is it a good or a risky habit to accept every permission? (a) risky habit (b) good habit
38. 38.🧮 A 6 V battery is joined to 12 Ω and 12 Ω resistors in series. What current flows (in amperes)? =
39. 39.⏱️ loop forever { LED ON; wait 50 ms; LED OFF; wait 350 ms }
    How many times does the LED blink in 4 seconds?
40. 40.⚡ A device works on 3 V and takes 0.1 A. What is its power (in watts)? =

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