Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 439 · 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.🧮 A 1.6 V battery is joined to 5 Ω and 3 Ω resistors in series. What current flows (in amperes)? =
2. 2.⚠️ Is it safe to stop if a part gets hot? (a) not safe (b) safe
3. 3.🧩 A capacitor in a circuit can … (a) make light (b) measure heat (c) store charge briefly (d) spin a wheel
4. 4.⏱️ How many milliseconds is a wait of 3.3 seconds?
5. 5.🔢 To get a sensor reading onto a phone, which is the FIRST step? (a) the board reads it (b) it is sent by Wi-Fi (c) the app shows it (d) the sensor measures
6. 6.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
7. 7.🔋 8 identical 1.5 V cells are joined in series, but one of them is put in the wrong way round. What is the total voltage now (in volts)? =
8. 8.✏️ In a circuit diagram, which part is drawn as a dot where wires meet? (a) battery (b) ammeter (c) junction (d) voltmeter
9. 9.🤖 if (temperature > 34) { show “Hot” } else if (temperature > 20) { show “Warm” } else { show “Cool” }
   The temperature is 20 °C. What is shown? (a) Hot (b) Cool (c) Warm
10. 10.True or false: if the switch is OFF, the circuit is open and no current flows. (a) False (b) True
11. 11.True or false: “the fan starts” is the input. (a) True (b) False
12. 12.What does a capacitor do? (a) boosts a small signal (b) stores a little charge (c) beeps for an alarm (d) turns a fan or wheels
13. 13.True or false: to fly kites in open fields is safe. (a) False (b) True
14. 14.Which of these is an insulator? (a) a copper wire (b) a ceramic cup (c) a safety pin (d) a brass key
15. 15.🧩 Which component makes things spin? (a) motor (b) transistor (c) LED (d) capacitor
16. 16.🧩 Which component blows if current is high? (a) capacitor (b) fuse (c) potentiometer (d) LDR
17. 17.🔘 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 ON and B is OFF. Does the bulb glow? (a) No (b) Yes
18. 18.🔺 A current of 50 mA flows through a 300 Ω resistor. What is the voltage across it (in volts)? =
19. 19.🤖 Where does the board keep its program when the power is off? (a) the USB cable (b) flash memory (c) the power LED (d) the resistor
20. 20.🔘 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 ON. Does the bulb glow? (a) No (b) Yes
21. 21.⚠️ Who should be with you when you build a circuit? (a) a younger child (b) nobody (c) a stranger online (d) a trusted adult
22. 22.🤖 if (distance < 30) { buzzer beeps } else { buzzer is silent }
    The distance sensor reads 30 cm. What happens? (a) buzzer beeps (b) buzzer is silent
23. 23.True or false: on a cell, “usually the black wire” means the − (negative) end. (a) False (b) True
24. 24.Which of these is safe? (a) poke things in a socket (b) dry your hands first (c) throw cells in a fire (d) touch a switch when wet
25. 25.⚠️ Is it safe to touch a fallen wire? (a) safe (b) not safe
26. 26.🔁 A bulb has two contacts. How many must be joined into the loop for it to glow? (a) it does not matter (b) only one (c) both of them (d) none
27. 27.🤖 “if (A AND B)” is true when … (a) both A and B are true (b) both are false (c) only A is true (d) only B is true
28. 28.🔺 A 2 V supply is joined across a 200 Ω resistor. What current flows (in milliamperes, mA)?
29. 29.🔍 Which is the odd one out? (a) a temperature reading (b) a motion sensor signal (c) an LED lights up (d) a button press
30. 30.📏 How many ohms (Ω) is 1.2 kΩ?
31. 31.🤖 if (temperature > 38) { show “Hot” } else if (temperature > 23) { show “Warm” } else { show “Cool” }
    The temperature is 42 °C. What is shown? (a) Warm (b) Cool (c) Hot
32. 32.Which of these means the circuit is closed? (a) the switch is ON (b) a wire has come loose (c) the bulb is unscrewed (d) the switch is OFF
33. 33.True or false: a tilt switch closes near a magnet. (a) True (b) False
34. 34.🔌 Is a servo motor an input or an output for a microcontroller? (a) input (b) output
35. 35.🧮 A 9 V battery is joined to 4 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
36. 36.🔋 Identical cells side by side (in parallel) give … (a) the same voltage (b) half the voltage (c) no voltage (d) double the voltage
37. 37.🔐 Is it a good or a risky habit to ignore update messages? (a) good habit (b) risky habit
38. 38.🔁 count = 4
    repeat 5 times { count = count + 8 }
    What is count at the end?
39. 39.💡 In a parallel circuit, one bulb breaks. What happens to the others? (a) they all go out (b) they get dimmer (c) they explode (d) they keep glowing
40. 40.⚡ A device works on 1.5 V and takes 0.25 A. What is its power (in watts)? =

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