Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 100 · 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.✏️ In a circuit diagram, wires are usually drawn as … (a) dotted circles (b) straight lines (c) little stars (d) wavy lines
2. 2.🧮 A 150 Ω resistor is joined in series with two equal 100 Ω resistors that are in parallel with each other. What is the total resistance (in ohms)?
3. 3.🔍 Which is the odd one out? (a) a torch (b) an electric kettle (c) a rice cooker (d) a room heater
4. 4.🔘 A bulb and a cell are joined through 6 switches on 6 side-by-side paths, one switch on each path (parallel). What is the smallest number of switches that must be ON to light the bulb?
5. 5.🤖 if (sound > 60) { red LED ON } else { green LED ON }
   The sound sensor reads 72. What happens? (a) green LED ON (b) red LED ON
6. 6.🔺 In the V-I-R triangle, how do we find V? (a) V = I + R (b) V = I ÷ R (c) V = I × R (d) V = R ÷ I
7. 7.Which job needs a sound sensor? (a) measure classroom noise (b) stop a robot near walls (c) keep an incubator warm (d) switch on lamps at dusk
8. 8.📏 Which unit measures resistance? (a) ampere (A) (b) volt (V) (c) ohm (Ω) (d) watt (W)
9. 9.🔌 Is a sound sensor an input or an output for a microcontroller? (a) input (b) output
10. 10.🔺 A current of 0.25 A flows through a 4 Ω resistor. What is the voltage across it (in volts)? =
11. 11.🧾 One “unit” on an electricity bill is … (a) 1 kilowatt-hour (kWh) (b) 1 ampere (c) 1 watt (d) 1 volt
12. 12.🧮 Two equal 20 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
13. 13.🧮 Adding another resistor in series makes the total resistance … (a) zero (b) smaller (c) bigger (d) stay the same
14. 14.What does a buzzer do? (a) limits the current (b) beeps for an alarm (c) has coloured bands (d) senses how hot it is
15. 15.Which of these is true of a parallel circuit? (a) used in house wiring (b) bulbs share the voltage (c) one bulb out, all go out (d) a single current path
16. 16.🔍 Which sensor would you use to open blinds at sunrise? (a) a light sensor (b) a distance sensor (c) a sound sensor (d) a soil moisture sensor
17. 17.💡 Why does an LED need a resistor in series? (a) to store charge (b) to change its colour (c) to make it brighter (d) to limit the current
18. 18.🔺 In the V-I-R triangle, how do we find I? (a) I = V × R (b) I = V + R (c) I = R ÷ V (d) I = V ÷ R
19. 19.True or false: a circle with a cross is the symbol for a cell. (a) False (b) True
20. 20.🧮 Two resistors in parallel give a total that is … (a) more than either one (b) always zero (c) less than either one (d) their sum
21. 21.🤖 if (light < 400) { lamp ON } else { lamp OFF }
    The light sensor reads 549. What happens? (a) lamp OFF (b) lamp ON
22. 22.🌐 A weather station sends one reading every 5 seconds. How many readings does it send in 2 minutes?
23. 23.Which drawing is the symbol for an ammeter? (a) a long and a short line (b) triangle against a bar (c) a circle with A inside (d) a small empty box
24. 24.True or false: a table fan mainly makes movement. (a) True (b) False
25. 25.🔢 To run one loop of a plant-watering program, which is the FIRST step? (a) read the soil sensor (b) wait a few seconds (c) switch the pump on/off (d) compare with the limit
26. 26.True or false: a fuse blows if current is high. (a) False (b) True
27. 27.🔢 To plan an electronics project, what comes right after “list inputs and outputs”? (a) test it and fix it (b) build it with an adult (c) draw the circuit diagram (d) pick a problem to solve
28. 28.🔌 A gap of dry air between two wires acts as … (a) a switch that is ON (b) a cell (c) an insulator (d) a conductor
29. 29.✏️ In a circuit diagram, which part is drawn as a long and a short line? (a) resistor (b) cell (c) motor (d) wire
30. 30.True or false: to close the fridge quickly saves electricity. (a) False (b) True
31. 31.🧮 Five equal 500 Ω resistors are joined in parallel. What is the total resistance (in ohms)?
32. 32.🧮 Resistors of 47 Ω, 220 Ω and 33 Ω are joined in series. What is the total resistance (in ohms)?
33. 33.True or false: on an LED, the round-side leg is the anode (+). (a) True (b) False
34. 34.Which of these is an insulator? (a) a dry cork (b) aluminium foil (c) a graphite rod (d) a metal paper clip
35. 35.📏 Voltmeter or ammeter: which one measures current? (a) voltmeter (b) ammeter
36. 36.True or false: “many paths for current” is true of a series circuit. (a) True (b) False
37. 37.🔍 Which sensor would you use to water a dry plant? (a) a rain sensor (b) a motion sensor (c) a gas sensor (d) a soil moisture sensor
38. 38.🔺 A current of 25 mA flows through a 200 Ω resistor. What is the voltage across it (in volts)? =
39. 39.🌈 In the resistor colour code, which number does orange stand for?
40. 40.🔢 To get a sensor reading onto a phone, which is the FIRST step? (a) it is sent by Wi-Fi (b) the sensor measures (c) the board reads it (d) the app shows it

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