Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 251 · 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 change default passwords? (a) risky habit (b) good habit
2. 2.🤖 “if (A AND B)” is true when … (a) only B is true (b) both are false (c) both A and B are true (d) only A is true
3. 3.🌈 A gold fourth band on a resistor means the value may be off by … (a) 5 % (b) 0 % (c) 25 % (d) 50 %
4. 4.True or false: a reed switch closes near a magnet. (a) True (b) False
5. 5.Which of these has no microcontroller inside? (a) a digital alarm clock (b) a smart watch (c) a plain wall switch (d) a digital thermometer
6. 6.🤖 if (distance < 10) { buzzer beeps } else { buzzer is silent }
   The distance sensor reads 19 cm. What happens? (a) buzzer is silent (b) buzzer beeps
7. 7.🔋 How many volts does one ordinary torch cell give? (a) 15 V (b) 1.5 V (c) 230 V (d) 0.5 V
8. 8.True or false: a wooden stick is an insulator. (a) True (b) False
9. 9.🔘 Which kind of switch stays where you flip it? (a) a toggle switch (b) a push button (c) a reed switch (d) a tilt switch
10. 10.✏️ In a cell symbol, which line is the + terminal? (a) both lines (b) neither line (c) the longer line (d) the shorter line
11. 11.🔺 A current of 40 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
12. 12.🧮 Resistors of 20 Ω and 68 Ω are joined in series. What is the total resistance (in ohms)?
13. 13.Which of these is true of a parallel circuit? (a) one bulb out, all go out (b) a break stops every bulb (c) a single current path (d) many paths for current
14. 14.🔋 How many 1.2 V cells must be joined in series to give 2.4 V?
15. 15.True or false: to turn off unused gadgets is a good habit. (a) True (b) False
16. 16.🔍 A distance sensor sends a sound pulse and hears the echo 4 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
17. 17.True or false: to read app permissions is a risky habit. (a) False (b) True
18. 18.💡 A red LED (it uses 2 V) is joined with a 200 Ω resistor to a 5 V supply. What current flows (in mA)?
19. 19.🔦 A circuit has a new cell, a good bulb and a switch that is ON. All the wires are firmly joined. Does the bulb glow? (a) No (b) Yes
20. 20.💡 A battery lights 5 identical bulbs joined in series. One more identical bulb is added in series. How do the bulbs glow now? (a) dimmer (b) the same (c) brighter
21. 21.Which of these means the circuit is open? (a) the switch is ON (b) all wires are joined (c) a cell is taken out (d) the loop is complete
22. 22.🔺 A current of 0.2 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
23. 23.🌐 A soil sensor sends a reading to an app every 15 minutes. How many readings arrive in 3 hours?
24. 24.Which job needs a motor? (a) turn to an exact angle (b) spin a robot’s wheels (c) move water to plants (d) beep an alarm
25. 25.🔘 Switch A is on the main wire next to the cell and the bulb; then the wire splits into two side-by-side paths, one with switch B and one with switch C. A is ON, B is OFF and C is OFF. Does the bulb glow? (a) Yes (b) No
26. 26.⏱️ How many milliseconds is a wait of 0.1 seconds?
27. 27.🤖 if (sound > 80) { red LED ON } else { green LED ON }
    The sound sensor reads 83. What happens? (a) green LED ON (b) red LED ON
28. 28.⏱️ loop forever { LED ON; wait 900 ms; LED OFF; wait 100 ms }
    How many times does the LED blink in 10 seconds?
29. 29.Which of these means the circuit is closed? (a) the switch is ON (b) a cell is taken out (c) a wire has come loose (d) a wire is cut
30. 30.🤖 In “if (temp > 30)”, what runs when temp is exactly 30? (a) the else part (b) the if part (c) both parts (d) neither part
31. 31.🔁 count = 2
    while (count < 14) { count = count + 3 }
    How many times does the loop run?
32. 32.Which of these is measured in volts (V)? (a) the flow of charge (b) resistance (c) voltage (d) power
33. 33.⏱️ loop forever { LED ON; wait 900 ms; LED OFF; wait 850 ms }
    How many milliseconds does one blink (ON + OFF) take?
34. 34.True or false: if all wires are joined, the circuit is closed and current flows. (a) True (b) False
35. 35.🗺️ In an input → process → output plan, is “count button presses” the input, the process or the output? (a) input (b) output (c) process
36. 36.🔐 A smart speaker is always listening for its wake word. What is a sensible habit? (a) let strangers use it (b) put it in the bathroom (c) mute it when not in use (d) tell it your passwords
37. 37.🔦 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 plastic straw. Does the bulb glow? (a) No (b) Yes
38. 38.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
39. 39.🔍 Which is the odd one out? (a) fly kites in open fields (b) use a cable with cuts (c) throw cells in a fire (d) climb an electric pole
40. 40.💡 A red LED uses 2 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?

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