Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 856 · 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 gives us electricity? (a) an air conditioner (b) a washing machine (c) a battery (d) a computer
2. 2.🌈 A gold fourth band on a resistor means the value may be off by … (a) 0 % (b) 50 % (c) 25 % (d) 5 %
3. 3.🔍 Which sensor would you use to switch on lamps at dusk? (a) a light sensor (b) a sound sensor (c) a distance sensor (d) a soil moisture sensor
4. 4.💡 A red LED uses 2 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
5. 5.🔺 A 10 V supply is joined across a 20 Ω resistor. What current flows (in amperes)? =
6. 6.🤖 if (light < 400 OR motion) { porch lamp ON } else { porch lamp OFF }
   The light reading is 230 and motion is not detected (false). What happens? (a) porch lamp ON (b) porch lamp OFF
7. 7.⏱️ loop forever { LED ON; wait 50 ms; LED OFF; wait 500 ms }
   How many milliseconds does one blink (ON + OFF) take?
8. 8.📏 In the water-pipe picture of a circuit, voltage is like … (a) the water pressure (b) the pipe colour (c) the water tank lid (d) the tap handle
9. 9.🔍 Which is the odd one out? (a) a motion sensor signal (b) a soil moisture reading (c) a button press (d) a buzzer beeps
10. 10.💡 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)?
11. 11.Which of these mainly gives out heat? (a) an LED lamp (b) an electric kettle (c) an electric drill (d) a street light
12. 12.🔋 2 identical 2 V cells are joined in series (+ of one cell to − of the next). What is the total voltage (in volts)? =
13. 13.🔺 A current of 3 A flows through a 5 Ω resistor. What is the voltage across it (in volts)? =
14. 14.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark a 7200 Ω resistor? (a) red-violet-red (b) violet-red-brown (c) violet-red-red (d) violet-red-orange
15. 15.💡 An LED is joined to a 5 V battery with no 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
16. 16.🔋 Does a solar panel give electricity or use electricity? (a) uses electricity (b) gives electricity
17. 17.🔢 To run one loop of a plant-watering program, which comes first: “read the soil sensor” or “compare with the limit”? (a) read the soil sensor (b) compare with the limit
18. 18.True or false: if the bulb is unscrewed, the circuit is open and no current flows. (a) False (b) True
19. 19.🧩 Which part changes electrical energy into sound? (a) a capacitor (b) a diode (c) a resistor (d) a buzzer
20. 20.True or false: triangle, bar and arrows is the symbol for an LED. (a) False (b) True
21. 21.🤖 “if (A AND B)” is true when … (a) only A is true (b) both A and B are true (c) only B is true (d) both are false
22. 22.Which of these is not an IoT device? (a) a smart energy meter (b) a fitness band with app (c) a Wi-Fi smart plug (d) a wind-up clock
23. 23.🔍 For a microcontroller, is a sensor an input or an output? (a) a power source (b) a fuse (c) an input (d) an output
24. 24.📶 Digital or analog: a button: pressed or not? (a) digital (b) analog
25. 25.True or false: the push of a cell is measured in amperes (A). (a) False (b) True
26. 26.🔺 A current of 25 mA flows through a 120 Ω resistor. What is the voltage across it (in volts)? =
27. 27.🔍 Which is the odd one out? (a) a button press (b) compare with a limit (c) a soil moisture reading (d) a temperature reading
28. 28.🔺 A 1.5 V supply is joined across a 6 Ω resistor. What current flows (in amperes)? =
29. 29.🔋 On a cell, does “the longer symbol line” mean the + end or the − end? (a) + (positive) (b) − (negative)
30. 30.True or false: to log out of shared phones is a good habit. (a) False (b) True
31. 31.🔺 A 6 V supply is joined across a 120 Ω resistor. What current flows (in milliamperes, mA)?
32. 32.True or false: “a single current path” is true of a series circuit. (a) False (b) True
33. 33.True or false: an exhaust fan mainly makes movement. (a) True (b) False
34. 34.💡 An LED is joined to a 3 V battery through a 470 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
35. 35.True or false: to use daylight to read saves electricity. (a) True (b) False
36. 36.🔌 Most metals are good … (a) insulators (b) batteries (c) conductors (d) magnets only
37. 37.🌐 A weather station sends one reading every 15 seconds. How many readings does it send in 9 minutes?
38. 38.🔗 Series or parallel circuit: “many paths for current”? (a) series (b) parallel
39. 39.🔍 Which is the odd one out? (a) ignore update messages (b) accept every permission (c) share only needed data (d) share the Wi-Fi key
40. 40.🔘 Which kind of switch works only while pressed? (a) a slide switch (b) a push button (c) a toggle switch (d) a tilt switch

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