Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 581 · 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.Which of these wastes electricity? (a) use LED lamps (b) close the fridge quickly (c) unplug idle chargers (d) iron one shirt at a time
2. 2.🤖 if (distance < 20) { buzzer beeps } else { buzzer is silent }
   The distance sensor reads 19 cm. What happens? (a) buzzer beeps (b) buzzer is silent
3. 3.⚡ A device works on 5 V and takes 1.5 A. What is its power (in watts)? =
4. 4.🔋 4 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)? =
5. 5.True or false: a rubber eraser is an insulator. (a) True (b) False
6. 6.🔘 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) Yes (b) No
7. 7.🔁 x = 4
   repeat 2 times { x = x × 2 }
   What is x at the end?
8. 8.Which of these mainly gives out heat? (a) a torch (b) a water heater (c) a school bell (d) a mixer grinder
9. 9.💡 3 identical bulbs are in parallel and each bulb has its own switch on its path. 1 of the switches is OFF and the rest are ON. How many bulbs glow?
10. 10.🧮 Resistors of 330 Ω, 50 Ω and 330 Ω are joined in series. What is the total resistance (in ohms)?
11. 11.💡 An LED (with its resistor) is on pin 8. All pins start LOW. The program runs once:
    set pin 8 HIGH
    set pin 8 HIGH
    set pin 7 HIGH
    Is the LED ON or OFF at the end? (a) OFF (b) ON
12. 12.🔍 Which is the odd one out? (a) a copper wire (b) a steel spoon (c) a safety pin (d) a rubber band
13. 13.🧩 Which component has coloured bands? (a) thermistor (b) transistor (c) resistor (d) buzzer
14. 14.🔋 3 identical 3 V cells are joined in series (+ of one cell to − of the next). What is the total voltage (in volts)? =
15. 15.🔁 x = 2
    repeat 3 times { x = x × 2 }
    What is x at the end?
16. 16.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 910 Ω resistor? (a) brown-white-brown (b) white-brown-red (c) white-brown-black (d) white-brown-brown
17. 17.🔋 4 identical 2 V cells are joined side by side in parallel (all + ends together, all − ends together). What is the voltage across them (in volts)? =
18. 18.🔺 In the V-I-R triangle, how do we find V? (a) V = I ÷ R (b) V = I + R (c) V = R ÷ I (d) V = I × R
19. 19.🔺 A current of 3 A flows when 18 V is joined across a resistor. What is its resistance (in ohms)?
20. 20.🔁 total = 0
    for i = 1 to 4 { total = total + i }
    What is total at the end?
21. 21.🔍 Which is the odd one out? (a) an LED (b) a turning knob (c) a keypad (d) a light sensor
22. 22.🔌 Is a small display an input or an output for a microcontroller? (a) input (b) output
23. 23.True or false: a motor turns a fan or wheels. (a) True (b) False
24. 24.🔦 A tester circuit has a new cell, a good bulb and wires with a gap between two clips. We put a dry cork across the gap. Does the bulb glow? (a) Yes (b) No
25. 25.🔋 5 identical 3 V cells are joined side by side in parallel (all + ends together, all − ends together). What is the voltage across them (in volts)? =
26. 26.🔍 Which is the odd one out? (a) set the AC to 24 °C (b) unplug idle chargers (c) leave the TV on standby (d) switch off empty rooms
27. 27.Which of these is an input? (a) a buzzer (b) a sound sensor (c) a water pump (d) an LED
28. 28.🔘 A cell and a bulb are joined to two side-by-side paths: path 1 has switches A and B one after another, path 2 has switch C. A is OFF, B is ON and C is ON. Does the bulb glow? (a) Yes (b) No
29. 29.What does a diode do? (a) lets current go one way (b) senses how hot it is (c) makes things spin (d) boosts a small signal
30. 30.Which drawing is the symbol for a voltmeter? (a) a straight line (b) triangle against a bar (c) many long-short pairs (d) a circle with V inside
31. 31.Which job needs a light sensor? (a) make a parking alarm (b) water a dry plant (c) open blinds at sunrise (d) measure classroom noise
32. 32.Which job needs a servo motor? (a) move water to plants (b) spin a robot’s wheels (c) turn to an exact angle (d) beep an alarm
33. 33.⚡ Which formula gives electric power? (a) P = V × I (b) P = V + I (c) P = V ÷ I (d) P = I ÷ V
34. 34.🔺 A 1 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
35. 35.True or false: on an LED, the longer leg is the anode (+). (a) False (b) True
36. 36.What does a capacitor do? (a) senses how bright it is (b) turns a fan or wheels (c) smooths a wobbly supply (d) has coloured bands
37. 37.⚠️ Is it safe to dry your hands first? (a) not safe (b) safe
38. 38.🔘 A bulb and a cell are joined through 3 switches one after another in a single loop (series). What is the smallest number of switches that must be ON to light the bulb?
39. 39.🤖 if (temperature > 31) { show “Hot” } else if (temperature > 23) { show “Warm” } else { show “Cool” }
    The temperature is 17 °C. What is shown? (a) Hot (b) Cool (c) Warm
40. 40.🔋 How many 1.5 V cells must be joined in series to give 7.5 V?

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