Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 90 · 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: a small empty box is the symbol for a resistor. (a) False (b) True
2. 2.💡 A blue LED uses 3 V and should get 25 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
3. 3.True or false: a torch mainly gives out heat. (a) False (b) True
4. 4.🔺 In the V-I-R triangle, how do we find R? (a) R = I ÷ V (b) R = V + I (c) R = V ÷ I (d) R = V × I
5. 5.Which of these is a conductor? (a) an iron nail (b) a woollen thread (c) a wooden stick (d) a plastic ruler
6. 6.🌈 Which band is read first on a resistor? (a) the gold band (b) the one nearest an end (c) the widest gap (d) any band
7. 7.🤖 What is a microcontroller? (a) a type of battery (b) a kind of bulb (c) a big desktop computer (d) a computer on one chip
8. 8.🔦 A tester circuit has a new cell, a good bulb and wires with a gap between two clips. We put a copper wire across the gap. Does the bulb glow? (a) No (b) Yes
9. 9.⏱️ loop forever { LED ON; wait 300 ms; LED OFF; wait 100 ms }
   How many times does the LED blink in 20 seconds?
10. 10.🔁 In an old-style bulb, which thin wire glows when current flows? (a) the filament (b) the glass (c) the switch (d) the base
11. 11.True or false: a copper wire is a conductor. (a) False (b) True
12. 12.🔺 A 6 V supply is joined across a 2 Ω resistor. What current flows (in amperes)? =
13. 13.⚡ A device works on 1.5 V and takes 0.2 A. What is its power (in watts)? =
14. 14.✏️ In a circuit diagram, which part is drawn as a small empty box? (a) motor (b) capacitor (c) resistor (d) voltmeter
15. 15.True or false: “a motion sensor signal” is the input. (a) False (b) True
16. 16.Which of these is not an IoT device? (a) an app-controlled bulb (b) a smart energy meter (c) a fitness band with app (d) a plain table fan
17. 17.🌐 Each reading a sensor sends is 20 bytes. How many bytes do 80 readings take?
18. 18.🌐 What does IoT stand for? (a) Inside of Toys (b) Input of Tools (c) Internet of Things (d) Internet of Talk
19. 19.🧩 Which component smooths a wobbly supply? (a) diode (b) transistor (c) fuse (d) capacitor
20. 20.🌈 In the resistor colour code, which number does white stand for?
21. 21.💡 A battery lights 5 identical bulbs joined in series. One more identical bulb is added in series. How do the bulbs glow now? (a) the same (b) brighter (c) dimmer
22. 22.🔍 Which is the odd one out? (a) a traffic signal (b) a torch (c) a tube light (d) a ceiling fan
23. 23.Which drawing is the symbol for a junction? (a) two equal parallel lines (b) a dot where wires meet (c) two or more cell symbols (d) a straight line
24. 24.⚠️ Is it safe to build with an adult near? (a) safe (b) not safe
25. 25.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 42 Ω resistor? (a) yellow-red-brown (b) yellow-red-black (c) red-yellow-black (d) green-red-black
26. 26.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) stay the same (d) bigger
27. 27.💡 In a series circuit, how many paths does the current have? (a) none (b) one (c) one for each bulb (d) two
28. 28.Which of these means the circuit is closed? (a) the bulb is unscrewed (b) the switch is ON (c) a cell is taken out (d) the switch is OFF
29. 29.True or false: “a break stops every bulb” is true of a series circuit. (a) False (b) True
30. 30.🔺 A current of 0.25 A flows when 1 V is joined across a resistor. What is its resistance (in ohms)?
31. 31.🔘 Which kind of switch slides side to side? (a) a reed switch (b) a tilt switch (c) a toggle switch (d) a slide switch
32. 32.💡 Old festival light strings went fully dark when one bulb failed. How were they joined? (a) not joined (b) in parallel (c) by Wi-Fi (d) in series
33. 33.🔺 A 20 V supply is joined across a 10 Ω resistor. What current flows (in amperes)? =
34. 34.⏱️ loop forever { LED ON; wait 650 ms; LED OFF; wait 650 ms }
    How many milliseconds does one blink (ON + OFF) take?
35. 35.🤖 In “if (temp > 30)”, what runs when temp is exactly 30? (a) both parts (b) the if part (c) neither part (d) the else part
36. 36.Which of these is safe? (a) dry your hands first (b) climb an electric pole (c) touch a fallen wire (d) use mains for a project
37. 37.🔋 Does a bicycle dynamo give electricity or use electricity? (a) uses electricity (b) gives electricity
38. 38.💡 On an LED, is the shorter leg the anode (+) or the cathode (−)? (a) anode (+) (b) cathode (−)
39. 39.🔺 A current of 20 mA flows through a 220 Ω resistor. What is the voltage across it (in volts)? =
40. 40.🔺 A current of 0.25 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =

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