Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 805 · 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 resistor has the colour bands violet, brown, black. What is its value (in ohms)?
2. 2.💡 A red LED (it uses 2 V) is joined with a 100 Ω resistor to a 3.5 V supply. What current flows (in mA)?
3. 3.Which of these mainly makes movement? (a) a table fan (b) a school bell (c) a siren (d) a rice cooker
4. 4.⏱️ loop forever { LED ON; wait 50 ms; LED OFF; wait 150 ms }
   How many times does the LED blink in 1 second?
5. 5.🔺 A current of 20 mA flows through a 470 Ω resistor. What is the voltage across it (in volts)? =
6. 6.True or false: a laptop uses very little power. (a) False (b) True
7. 7.🤖 if (sound > 60) { red LED ON } else { green LED ON }
   The sound sensor reads 69. What happens? (a) green LED ON (b) red LED ON
8. 8.🔌 Is a keypad an input or an output for a microcontroller? (a) output (b) input
9. 9.🔋 On a cell, does “usually the red wire” mean the + end or the − end? (a) − (negative) (b) + (positive)
10. 10.🤖 if (temperature > 30) { show “Hot” } else if (temperature > 21) { show “Warm” } else { show “Cool” }
    The temperature is 38 °C. What is shown? (a) Warm (b) Hot (c) Cool
11. 11.True or false: “many values in a range” is an analog signal. (a) True (b) False
12. 12.🔁 What does “count = count + 1” do? (a) sets count to 1 (b) adds 1 to count (c) prints 1 (d) takes 1 away
13. 13.True or false: to leave fridge door open wastes electricity. (a) True (b) False
14. 14.Which of these is not safe? (a) stay away from pylons (b) use small battery cells (c) dry your hands first (d) fly a kite near wires
15. 15.🔋 How many 3 V cells must be joined in series to give 12 V?
16. 16.🔺 A current of 10 mA flows when 2.5 V is joined across a resistor. What is its resistance (in ohms)?
17. 17.🧮 Four equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
18. 18.✏️ In a circuit diagram, which part is drawn as a line lifted at a gap? (a) switch (b) diode (c) motor (d) bulb
19. 19.🌈 A resistor has the colour bands white, black, black. What is its value (in ohms)?
20. 20.Which of these is safe? (a) touch a switch when wet (b) fly a kite near wires (c) climb an electric pole (d) build with an adult near
21. 21.💡 In a parallel circuit, one bulb breaks. What happens to the others? (a) they all go out (b) they keep glowing (c) they get dimmer (d) they explode
22. 22.⚡ A home appliance on the 230 V mains takes 1.5 A. What is its power (in watts)?
23. 23.🔦 A tester circuit has a new cell, a good bulb and wires with a gap between two clips. We put a graphite rod across the gap. Does the bulb glow? (a) Yes (b) No
24. 24.True or false: “each gets the full volts” is true of a series circuit. (a) True (b) False
25. 25.True or false: an LDR senses how bright it is. (a) True (b) False
26. 26.⚡ Which formula gives electric power? (a) P = I ÷ V (b) P = V + I (c) P = V × I (d) P = V ÷ I
27. 27.⏱️ repeat 6 times { buzzer ON; wait 100 ms; buzzer OFF; wait 900 ms }
    How many milliseconds does this take in all?
28. 28.⚠️ Who should be with you when you build a circuit? (a) nobody (b) a younger child (c) a stranger online (d) a trusted adult
29. 29.🔌 Is a metal paper clip a conductor or an insulator? (a) an insulator (b) a conductor
30. 30.⏱️ A program says “wait 3750 ms”. How many seconds is that? =
31. 31.📏 How many amperes (A) is 2430 mA? =
32. 32.🌈 In the resistor colour code, which number does green stand for?
33. 33.📏 Voltmeter or ammeter: which one measures voltage? (a) voltmeter (b) ammeter
34. 34.🗺️ Before building a project, what should you write down first? (a) the box colour (b) inputs and outputs (c) the final price (d) nothing at all
35. 35.💡 2 identical bulbs are joined in parallel across a 3 V battery (ideal wires). How many volts does each bulb get? =
36. 36.💡 3 identical bulbs are joined in series with a battery and a closed switch on the main wire. Bulb 2 is taken out of its holder. How many bulbs glow?
37. 37.⚡ A home appliance on the 230 V mains takes 4 A. What is its power (in watts)?
38. 38.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
39. 39.Which drawing is the symbol for a cell? (a) a circle with M inside (b) a line lifted at a gap (c) a circle with an X in it (d) a long and a short line
40. 40.🔘 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 ON, B is OFF and C is OFF. Does the bulb glow? (a) No (b) Yes

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