Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 289 · 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 current of 25 mA flows when 7.5 V is joined across a resistor. What is its resistance (in ohms)?
2. 2.🔺 A 10 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
3. 3.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
4. 4.🔁 What does “count = count + 1” do? (a) prints 1 (b) adds 1 to count (c) takes 1 away (d) sets count to 1
5. 5.💡 2 identical bulbs are joined in series with a battery and a closed switch on the main wire. Bulb 1 is taken out of its holder. Does bulb 2 glow? (a) Yes (b) No
6. 6.True or false: “a door: open or shut” is a digital signal. (a) False (b) True
7. 7.🔢 To run one loop of a plant-watering program, what comes right after “read the soil sensor”? (a) wait a few seconds (b) compare with the limit (c) switch the pump on/off
8. 8.🔦 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 wooden stick. Does the bulb glow? (a) Yes (b) No
9. 9.💡 5 identical bulbs are joined in series with a 7.5 V battery (ideal wires). How many volts does each bulb get? =
10. 10.True or false: a safety pin is an insulator. (a) False (b) True
11. 11.True or false: a push button springs back when let go. (a) True (b) False
12. 12.✏️ In a circuit diagram, which part is drawn as a long and a short line? (a) bulb (b) junction (c) cell (d) wire
13. 13.🔺 A current of 0.2 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🔋 Does a power station give electricity or use electricity? (a) gives electricity (b) uses electricity
15. 15.📶 Digital or analog: a door: open or shut? (a) digital (b) analog
16. 16.🧮 A 1.5 V battery is joined to 10 Ω and 5 Ω resistors in series. What current flows (in amperes)? =
17. 17.🤖 if (temperature > 38) { show “Hot” } else if (temperature > 21) { show “Warm” } else { show “Cool” }
    The temperature is 20 °C. What is shown? (a) Cool (b) Warm (c) Hot
18. 18.⚡ A home appliance on the 230 V mains takes 10 A. What is its power (in watts)?
19. 19.🔺 A 7.5 V supply is joined across a 300 Ω resistor. What current flows (in milliamperes, mA)?
20. 20.⏱️ How many milliseconds is a wait of 2.8 seconds?
21. 21.🔺 A current of 3 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
22. 22.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
23. 23.🔺 A current of 0.2 A flows when 1.2 V is joined across a resistor. What is its resistance (in ohms)?
24. 24.True or false: a microwave oven has no microcontroller inside. (a) False (b) True
25. 25.🔦 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 steel spoon. Does the bulb glow? (a) Yes (b) No
26. 26.💡 A battery lights 3 identical bulbs joined in series. One more identical bulb is added in series. How do the bulbs glow now? (a) the same (b) dimmer (c) brighter
27. 27.✏️ In a circuit diagram, wires are usually drawn as … (a) dotted circles (b) straight lines (c) little stars (d) wavy lines
28. 28.🔺 A current of 20 mA flows through a 400 Ω resistor. What is the voltage across it (in volts)? =
29. 29.🌐 A soil sensor sends a reading to an app every 5 minutes. How many readings arrive in 6 hours?
30. 30.True or false: to fly a kite near wires is safe. (a) True (b) False
31. 31.🔺 In the V-I-R triangle, how do we find V? (a) V = R ÷ I (b) V = I + R (c) V = I × R (d) V = I ÷ R
32. 32.🔍 Which is the odd one out? (a) a water pump (b) a small display (c) a motion sensor (d) an LED
33. 33.✏️ In a cell symbol, which line is the + terminal? (a) the shorter line (b) both lines (c) neither line (d) the longer line
34. 34.🔋 On a cell, does “the flat end” mean the + end or the − end? (a) + (positive) (b) − (negative)
35. 35.🔁 What do we call a circuit with a break in it? (a) a closed circuit (b) an open circuit (c) a series circuit (d) a full circuit
36. 36.💡 An LED is joined to a 5 V battery through a 1000 Ω resistor; the leg next to the flat edge of its rim goes to the − side. What happens? (a) may burn out (b) lights up (c) does not light
37. 37.🔍 Which is the odd one out? (a) check if temp > 30 (b) compare with a limit (c) a buzzer beeps (d) decide if soil is dry
38. 38.⏱️ loop forever { LED ON; wait 100 ms; LED OFF; wait 100 ms }
    How many times does the LED blink in 10 seconds?
39. 39.True or false: to use daylight to read wastes electricity. (a) True (b) False
40. 40.💡 Why does an LED need a resistor in series? (a) to change its colour (b) to limit the current (c) to store charge (d) to make it brighter

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