Electronics Worksheet: Final Test

Electronics lesson 30: Final electronics test · Set 420 · 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.🔺 A current of 0.2 A flows through a 2 Ω resistor. What is the voltage across it (in volts)? =
2. 2.🔍 Which is the odd one out? (a) a traffic signal (b) a torch (c) a street light (d) a rice cooker
3. 3.🔍 Which is the odd one out? (a) a soil moisture reading (b) a light level reading (c) a motion sensor signal (d) decide if soil is dry
4. 4.⚠️ Why must we never touch switches with wet hands? (a) it spoils the paint (b) water makes it cold (c) it is just untidy (d) water carries current
5. 5.⏱️ loop forever { LED ON; wait 450 ms; LED OFF; wait 250 ms }
   How many milliseconds does one blink (ON + OFF) take?
6. 6.🔁 repeat 3 times { repeat 3 times { beep } }
   How many beeps are there?
7. 7.What does a reed switch do? (a) springs back when let go (b) works only while pressed (c) closes near a magnet (d) stays where you flip it
8. 8.🔺 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
9. 9.🌈 Which band is read first on a resistor? (a) the gold band (b) the widest gap (c) any band (d) the one nearest an end
10. 10.🤖 if (light < 200 AND motion) { porch lamp ON } else { porch lamp OFF }
    The light reading is 510 and motion is detected (true). What happens? (a) porch lamp ON (b) porch lamp OFF
11. 11.⚡ A device works on 5 V and takes 0.2 A. What is its power (in watts)? =
12. 12.True or false: a toaster mainly gives out light. (a) False (b) True
13. 13.🌐 A weather station sends one reading every 10 seconds. How many readings does it send in 9 minutes?
14. 14.🔺 A current of 20 mA flows through a 100 Ω resistor. What is the voltage across it (in volts)? =
15. 15.Which job needs a motion sensor? (a) water a dry plant (b) spot someone walking in (c) switch on with a clap (d) make a parking alarm
16. 16.🧮 A 10 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)?
17. 17.🔘 A bulb and a cell are joined through 4 switches one after another in a single loop (series). What is the smallest number of switches that must be ON to light the bulb?
18. 18.💡 6 identical bulbs are joined in series with a battery and a closed switch on the main wire. Bulb 5 is taken out of its holder. Does bulb 6 glow? (a) Yes (b) No
19. 19.🌐 A weather station sends one reading every 5 seconds. How many readings does it send in 1 minute?
20. 20.💡 5 identical bulbs are joined in parallel (each on its own side-by-side path) with a battery and a closed switch on the main wire. Bulb 4 is taken out of its holder. Does bulb 2 glow? (a) No (b) Yes
21. 21.⏱️ What does “wait 500 ms” do? (a) blinks 500 times (b) turns the LED off (c) waits 500 seconds (d) pauses for half a second
22. 22.Which of these is true of a parallel circuit? (a) own switch for each bulb (b) a single current path (c) a break stops every bulb (d) one bulb out, all go out
23. 23.🔁 Is the circuit closed or open if the switch is OFF? (a) closed (b) open
24. 24.⚡ A fan changes electrical energy mainly into which kind of energy? (a) light energy (b) chemical energy (c) sound energy (d) movement energy
25. 25.⚡ Which formula gives electric power? (a) P = V × I (b) P = V ÷ I (c) P = V + I (d) P = I ÷ V
26. 26.🔍 A distance sensor sends a sound pulse and hears the echo 18 ms later. Sound travels about 34 cm every millisecond. How far away is the object (in cm)?
27. 27.⏱️ How many milliseconds is a wait of 2.3 seconds?
28. 28.⏱️ How many milliseconds are in 1 second? (a) 10 (b) 1000 (c) 100 (d) 60
29. 29.🌈 A resistor has the colour bands blue, brown, yellow. What is its value in kilo-ohms (kΩ)? =
30. 30.⚡ A device works on 12 V and takes 0.1 A. What is its power (in watts)? =
31. 31.True or false: on an LED, the shorter leg is the anode (+). (a) False (b) True
32. 32.🔺 A current of 0.5 A flows through a 6 Ω resistor. What is the voltage across it (in volts)? =
33. 33.🧩 Which component makes a beeping sound? (a) transistor (b) potentiometer (c) thermistor (d) buzzer
34. 34.True or false: a mixer grinder mainly gives out light. (a) True (b) False
35. 35.🔺 The voltage stays the same and the resistance gets bigger. The current … (a) stays the same (b) gets smaller (c) becomes zero (d) gets bigger
36. 36.True or false: a circle with V inside is the symbol for a voltmeter. (a) False (b) True
37. 37.True or false: to leave the TV on standby saves electricity. (a) True (b) False
38. 38.Which of these wastes electricity? (a) switch off empty rooms (b) close the fridge quickly (c) use old filament bulbs (d) use daylight to read
39. 39.🧮 Two resistors in parallel give a total that is … (a) always zero (b) less than either one (c) their sum (d) more than either one
40. 40.💡 A blue LED uses 3 V and should get 10 mA. It runs from a 6 V supply. What resistor (in ohms) is needed in series?

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