Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 539 · 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.True or false: to open a phone charger is not safe. (a) True (b) False
2. 2.💡 An LED (with its resistor) is on pin 8. All pins start LOW. The program runs once:
   set pin 7 LOW
   set pin 8 LOW
   set pin 8 HIGH
   Is the LED ON or OFF at the end? (a) OFF (b) ON
3. 3.🔍 Which is the odd one out? (a) ignore update messages (b) keep factory passwords (c) cover unused cameras (d) share the Wi-Fi key
4. 4.🔺 A current of 1 A flows through a 15 Ω resistor. What is the voltage across it (in volts)? =
5. 5.🔺 A current of 50 mA flows when 25 V is joined across a resistor. What is its resistance (in ohms)?
6. 6.⚠️ A cell gets hot when its + and − ends are joined by a bare wire. What is this called? (a) a short circuit (b) a parallel circuit (c) an open circuit (d) a safe circuit
7. 7.Which job needs a servo motor? (a) spin a robot’s wheels (b) show a status light (c) move water to plants (d) turn to an exact angle
8. 8.⚙️ Which actuator would you use to turn to an exact angle? (a) a buzzer (b) a motor (c) a pump (d) a servo motor
9. 9.🔺 A current of 20 mA flows when 3 V is joined across a resistor. What is its resistance (in ohms)?
10. 10.🔋 How many 1.5 V cells must be joined in series to give 7.5 V?
11. 11.Which job needs a light sensor? (a) warn of a gas leak (b) spot someone walking in (c) switch on lamps at dusk (d) switch on with a clap
12. 12.Which of these is true of a series circuit? (a) each gets the full volts (b) one out, the rest glow (c) many paths for current (d) a break stops every bulb
13. 13.⏱️ loop forever { LED ON; wait 500 ms; LED OFF; wait 700 ms }
    How many milliseconds does one blink (ON + OFF) take?
14. 14.💡 Why is house wiring done in parallel? (a) to save copper only (b) so all go off together (c) each gets full voltage (d) to make bulbs dim
15. 15.Which of these is an output? (a) a motion sensor (b) a keypad (c) a temperature sensor (d) a buzzer
16. 16.🔺 A current of 2.5 A flows through a 10 Ω resistor. What is the voltage across it (in volts)? =
17. 17.Which of these has no microcontroller inside? (a) a washing machine (b) a TV remote (c) a toy robot (d) a spinning top
18. 18.🔺 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
19. 19.🔺 A current of 10 mA flows through a 500 Ω resistor. What is the voltage across it (in volts)? =
20. 20.True or false: “used in house wiring” is true of a series circuit. (a) True (b) False
21. 21.🔐 Why install updates on IoT devices? (a) they fix security holes (b) they change the colour (c) they delete the Wi-Fi (d) they make it heavier
22. 22.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
23. 23.What does a motor do? (a) blows if current is high (b) has coloured bands (c) stores a little charge (d) makes things spin
24. 24.🔘 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 OFF, B is ON and C is OFF. Does the bulb glow? (a) No (b) Yes
25. 25.True or false: a microcontroller runs one small program. (a) False (b) True
26. 26.Which of these uses electricity? (a) a power station (b) a generator (c) a solar panel (d) a washing machine
27. 27.🔍 For a microcontroller, is a sensor an input or an output? (a) a power source (b) a fuse (c) an input (d) an output
28. 28.🧩 A capacitor in a circuit can … (a) spin a wheel (b) measure heat (c) store charge briefly (d) make light
29. 29.🔁 count = 5
    repeat 2 times { count = count + 3 }
    What is count at the end?
30. 30.🔘 A cell, a bulb and switches A, B, C and D are joined one after another in a single loop (series). A is OFF, B is OFF, C is OFF and D is OFF. Does the bulb glow? (a) Yes (b) No
31. 31.🧩 Which component makes things spin? (a) motor (b) capacitor (c) diode (d) transistor
32. 32.Which of these mainly gives out heat? (a) a loudspeaker (b) a tube light (c) a mixer grinder (d) an electric iron
33. 33.Which of these is an insulator? (a) a brass key (b) aluminium foil (c) a glass marble (d) an iron nail
34. 34.📏 Which unit measures energy used each second? (a) volt (V) (b) watt (W) (c) ampere (A) (d) ohm (Ω)
35. 35.🔺 A 20 V supply is joined across an 8 Ω resistor. What current flows (in amperes)? =
36. 36.🤖 if (light < 300 AND motion) { porch lamp ON } else { porch lamp OFF }
    The light reading is 300 and motion is detected (true). What happens? (a) porch lamp ON (b) porch lamp OFF
37. 37.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 910 Ω resistor? (a) white-brown-black (b) white-brown-brown (c) white-brown-red (d) brown-white-brown
38. 38.What does a push button do? (a) slides side to side (b) works only while pressed (c) closes when tipped over (d) flips up or down
39. 39.✏️ Why do engineers draw circuits with symbols? (a) to hide the circuit (b) quick and clear for all (c) to make it colourful (d) symbols are heavier
40. 40.🔁 repeat 4 times { repeat 2 times { beep } }
    How many beeps are there?

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