Virtual Labs

To simulate interfacing of multiple sensors (Ultrasonic sensor, PIR Sensor, DHT sensor, Soil Moisture, MQ135 Sensors) with Arduino.

1. How do ultrasonic sensors measure distance?

a: By detecting heat from objects Explanation

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b: By measuring time taken for sound waves to return Explanation

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c: By reading infrared radiation Explanation

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d: By using GPS signals Explanation

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2. Why does a PIR sensor sometimes give false triggers?

a: Because it uses sound waves Explanation

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b: Due to sudden temperature changes or noise Explanation

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c: Because it detects magnetic fields Explanation

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d: Because it requires constant calibration Explanation

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3. How does a DHT sensor transfer digital data?

a: Using single-wire digital communication Explanation

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b: Using I2C protocol Explanation

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c: Using ultrasonic pulses Explanation

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d: Using analog voltage levels Explanation

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4. How can soil moisture readings be used in smart irrigation?

a: To measure sunlight levels Explanation

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b: To automatically control water supply Explanation

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c: To detect air pollution Explanation

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d: To detect motion in the field Explanation

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5. Why is the MQ135 sensor important in pollution monitoring?

a: It detects humidity accurately Explanation

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b: It detects harmful gases in the air Explanation

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c: It measures sound levels Explanation

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d: It measures soil nutrients Explanation

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6. How do PIR and ultrasonic sensors differ in motion detection?

a: PIR detects heat motion, ultrasonic detects distance changes Explanation

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b: Both detect motion using sound waves Explanation

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c: Both detect motion using heat Explanation

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d: PIR uses sound, ultrasonic uses light Explanation

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7. What is the role of calibration in an MQ135 sensor?

a: To adjust humidity readings Explanation

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b: To accurately detect gas concentration levels Explanation

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c: To measure temperature more precisely Explanation

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d: To reduce soil moisture errors Explanation

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8. How does temperature affect DHT sensor accuracy?

a: It has no effect Explanation

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b: Extreme temperatures decrease accuracy Explanation

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c: Higher temperature increases the sensor size Explanation

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d: Temperature has no relation to humidity readings Explanation

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9. Why do soil moisture sensor values fluctuate?

a: Because soil conductivity changes with water distribution Explanation

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b: Because GPS signals affect it Explanation

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c: Because it measures air humidity inside soil Explanation

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d: Because it uses ultrasonic waves Explanation

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10. Which IoT application uses two sensors together effectively?

a: Smart security using PIR + Ultrasonic Explanation

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b: Soil testing using PIR + MQ135 Explanation

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c: Distance measurement using DHT + PIR Explanation

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d: Smart lighting using MQ135 + Soil sensor Explanation

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