Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 937 · 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.⏱️ loop forever { LED ON; wait 150 ms; LED OFF; wait 350 ms }
   How many times does the LED blink in 4 seconds?
2. 2.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 watt (c) 1 ampere (d) 1 volt
3. 3.🔺 A current of 25 mA flows when 6.25 V is joined across a resistor. What is its resistance (in ohms)?
4. 4.🔗 Series or parallel circuit: “a single current path”? (a) series (b) parallel
5. 5.🌈 In the resistor colour code, which number does orange stand for?
6. 6.Which of these gives us electricity? (a) a computer (b) a mobile phone (c) a television (d) a battery
7. 7.🔘 Which kind of switch springs back when let go? (a) a push button (b) a reed switch (c) a slide switch (d) a toggle switch
8. 8.💡 In a parallel circuit, one bulb breaks. What happens to the others? (a) they all go out (b) they explode (c) they get dimmer (d) they keep glowing
9. 9.✏️ In a circuit diagram, which part is drawn as a circle with an X in it? (a) motor (b) bulb (c) resistor (d) switch
10. 10.💡 A blue LED uses 3 V and should get 20 mA. It runs from a 5 V supply. What resistor (in ohms) is needed in series?
11. 11.🔘 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 OFF, B is ON and C is OFF. Does the bulb glow? (a) No (b) Yes
12. 12.🔌 A gap of dry air between two wires acts as … (a) a switch that is ON (b) an insulator (c) a conductor (d) a cell
13. 13.🌈 Which colour bands (1st digit, 2nd digit, multiplier) mark an 88 Ω resistor? (a) grey-grey-brown (b) grey-white-black (c) white-grey-black (d) grey-grey-black
14. 14.🔘 Which kind of switch closes when tipped over? (a) a toggle switch (b) a reed switch (c) a slide switch (d) a tilt switch
15. 15.🌈 Which band is read first on a resistor? (a) any band (b) the one nearest an end (c) the widest gap (d) the gold band
16. 16.🤖 What is a microcontroller? (a) a type of battery (b) a kind of bulb (c) a computer on one chip (d) a big desktop computer
17. 17.🔘 Two switches are in parallel (side by side). When does the bulb glow? (a) only when both are ON (b) only when both are OFF (c) never (d) when either is ON
18. 18.🤖 if (moisture < 40) { pump ON } else { pump OFF }
    The soil moisture sensor reads 25 %. What happens? (a) pump OFF (b) pump ON
19. 19.⚡ A 0.15 W device works on 1.5 V. What current does it take (in amperes)? =
20. 20.🔍 A distance sensor sends a sound pulse and hears the echo 10 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
21. 21.🔢 To run one loop of a plant-watering program, which comes first: “switch the pump on/off” or “wait a few seconds”? (a) switch the pump on/off (b) wait a few seconds
22. 22.🔢 To plan an electronics project, which is the LAST step? (a) test it and fix it (b) list inputs and outputs (c) pick a problem to solve (d) build it with an adult
23. 23.🔦 A circuit has a new cell, a good bulb and a switch that is ON. One wire has come loose from the cell. Does the bulb glow? (a) No (b) Yes
24. 24.🔘 A cell and a bulb are joined to 3 side-by-side paths with one switch on each path — A, B and C (parallel). A is OFF, B is OFF and C is OFF. Does the bulb glow? (a) Yes (b) No
25. 25.Which job needs a pump? (a) move water to plants (b) open a gate to 90° (c) beep an alarm (d) show the temperature
26. 26.🔍 Which is the odd one out? (a) ignore update messages (b) set up with a parent (c) install software updates (d) cover unused cameras
27. 27.💡 Why does an LED need a resistor in series? (a) to store charge (b) to change its colour (c) to limit the current (d) to make it brighter
28. 28.🔺 A 13.2 V supply is joined across a 330 Ω resistor. What current flows (in milliamperes, mA)?
29. 29.Which of these mainly gives out heat? (a) a street light (b) an LED lamp (c) a torch (d) a room heater
30. 30.⚡ What does an LED lamp mainly change electricity into? (a) light (b) heat (c) sound (d) movement
31. 31.🔘 What does a switch do in a circuit? (a) opens or closes the loop (b) changes the voltage (c) stores current (d) makes electricity
32. 32.True or false: a circle with an X in it is the symbol for a voltmeter. (a) False (b) True
33. 33.⚡ A home appliance on the 230 V mains takes 0.5 A. What is its power (in watts)?
34. 34.🔁 count = 2
    while (count < 14) { count = count + 3 }
    How many times does the loop run?
35. 35.⏱️ What does “wait 500 ms” do? (a) waits 500 seconds (b) turns the LED off (c) pauses for half a second (d) blinks 500 times
36. 36.⏱️ loop forever { LED ON; wait 900 ms; LED OFF; wait 100 ms }
    How many times does the LED blink in 1 second?
37. 37.🔋 8 identical 1.5 V cells are joined in series, but one of them is put in the wrong way round. What is the total voltage now (in volts)? =
38. 38.🔺 A current of 50 mA flows through a 250 Ω resistor. What is the voltage across it (in volts)? =
39. 39.⚡ A 12 W device works on 24 V. What current does it take (in amperes)? =
40. 40.⏱️ A program says “wait 8250 ms”. How many seconds is that? =

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