Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 338 · 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.🔐 Who should decide which smart devices go in a child’s room? (a) a parent or guardian (b) the app’s adverts (c) nobody at all (d) an online stranger
2. 2.💡 An LED is joined to a 3 V battery through a 220 Ω resistor; its long leg goes to the − side and its short leg to the + side. What happens? (a) may burn out (b) does not light (c) lights up
3. 3.⚡ Power tells us … (a) energy used each second (b) the colour of light (c) the length of a wire (d) the size of a cell
4. 4.🧮 A 470 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
5. 5.Which of these usually has a microcontroller inside? (a) a hand pump (b) a wind-up toy (c) a washing machine (d) a bicycle bell
6. 6.⏱️ loop forever { LED ON; wait 100 ms; LED OFF; wait 900 ms }
   How many times does the LED blink in 5 seconds?
7. 7.🧾 One “unit” on an electricity bill is … (a) 1 volt (b) 1 watt (c) 1 kilowatt-hour (kWh) (d) 1 ampere
8. 8.True or false: on an LED, the leg by the flat edge is the anode (+). (a) False (b) True
9. 9.🔋 What should you do with used-up cells? (a) throw them in a fire (b) give them for recycling (c) bury them in soil (d) cut them open
10. 10.🔁 count = 4
    while (count < 10) { count = count + 2 }
    How many times does the loop run?
11. 11.✏️ In a cell symbol, which line is the + terminal? (a) neither line (b) the shorter line (c) both lines (d) the longer line
12. 12.⚡ A 2.4 W device works on 12 V. What current does it take (in amperes)? =
13. 13.💡 5 identical bulbs are joined in series with a 12.5 V battery (ideal wires). How many volts does each bulb get? =
14. 14.True or false: to start a fan when hot, use a motion sensor. (a) True (b) False
15. 15.🔍 Which is the odd one out? (a) use mains for a project (b) poke things in a socket (c) use small battery cells (d) touch a switch when wet
16. 16.Which drawing is the symbol for a voltmeter? (a) triangle, bar and arrows (b) a circle with V inside (c) a long and a short line (d) two or more cell symbols
17. 17.🔺 A 6 V supply is joined across a 150 Ω resistor. What current flows (in milliamperes, mA)?
18. 18.🧮 Adding another resistor in series makes the total resistance … (a) stay the same (b) smaller (c) zero (d) bigger
19. 19.💡 3 identical bulbs are joined in parallel across a 1.5 V battery (ideal wires). How many volts does each bulb get? =
20. 20.Which of these is not safe? (a) keep drinks far away (b) build with an adult near (c) touch a fallen wire (d) use small battery cells
21. 21.Which of these is an input? (a) a light sensor (b) a speaker (c) a buzzer (d) an LED
22. 22.💡 In a series circuit, how many paths does the current have? (a) one for each bulb (b) two (c) none (d) one
23. 23.📏 In the water-pipe picture of a circuit, voltage is like … (a) the tap handle (b) the water pressure (c) the pipe colour (d) the water tank lid
24. 24.🔍 Which is the odd one out? (a) a servo motor (b) a light sensor (c) a sound sensor (d) a turning knob
25. 25.💡 An LED is joined to a 6 V battery through a 1000 Ω resistor; its long leg goes to the + side and its short leg to the − side. What happens? (a) may burn out (b) does not light (c) lights up
26. 26.🔺 A current of 0.2 A flows when 0.4 V is joined across a resistor. What is its resistance (in ohms)?
27. 27.🌐 In an IoT system, which part reads values, decides? (a) cloud server (b) microcontroller (c) actuator (d) phone app
28. 28.🤖 if (light < 400 OR motion) { porch lamp ON } else { porch lamp OFF }
    The light reading is 180 and motion is not detected (false). What happens? (a) porch lamp ON (b) porch lamp OFF
29. 29.True or false: to change default passwords is a risky habit. (a) True (b) False
30. 30.⏱️ How many milliseconds is a wait of 3.9 seconds?
31. 31.📏 How many kilowatts (kW) is 1500 W? =
32. 32.🧮 A 33 Ω resistor is joined in series with two equal 220 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
33. 33.🌐 Is a smart energy meter an IoT device? (a) not an IoT device (b) an IoT device
34. 34.🧮 A 330 Ω resistor is joined in series with two equal 40 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
35. 35.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
36. 36.True or false: a laptop has no screen of its own. (a) False (b) True
37. 37.Which of these gives us electricity? (a) an air conditioner (b) a washing machine (c) a mobile phone (d) a battery
38. 38.💡 What happens if an LED is put in backwards? (a) it lights brighter (b) it makes a sound (c) it does not light (d) it changes colour
39. 39.🔋 How many 1.5 V cells must be joined in series to give 9 V?
40. 40.🔁 count = 0
    repeat 7 times { count = count + 6 }
    What is count at the end?

Free electronics lessons, practice and worksheets at talentjr.in/electronics-for-kids