Which one of the following sensors is used for the automatic door opening system?

• a) PIR

• b) Ultrasonic

• c) Temperature

• d) Gas sensor

The operating principle of infrared sensors is ______________?

• a) Doppler effect

• b) Raman effect

• c) Pyroelectric effect

• d) Fluoresce effect

Which type of lens is generally used in the PIR sensors?

• a) Concave lens

• b) Convex lens

• c) Bifocal lens

• d) Fresnel Lens

The distance range of detection of the PIR sensor is ________

• a) 5-10 cm

• b)  5-7 m

• c) Up to 12 m

• d) 5-12 cm

PIR sensor detects the ________ of a person or object when it comes in close proximity

• a) Distance

• b) Heat

• c) Location

• d) Range

What is the use of the LDR Sensor?

• a) Monitors motion

• b) Monitors air pressure

• c) Monitors light intensity

• d) Monitors heartbeat

Photoconductivity is an optical phenomenon in which the material’s conductivity is increased when ________ is absorbed by the material.

• a) Heat

• b) Light

• c) Motion

• d) Sound

What is the frequency range of the ultrasonic sound waves used by the ultrasonic sensors?

• a) 20000Hz to 25000Hz

• b) 25KHz to 50KHz

• c) 25Hz to 55Hz

• d) 25Hz to 50Hz

Which of the following is the formula is used for calculating the distance (L) in ultrasonic sensors, where T – time and C – wave speed

• a) L = T/2 × C

• b) L = 1/2 × (T / C)

• c) L = 1/2 × (C / T)

• d) L = 1/2 × (T × C)

If 1 means an object is detected and 0 meaning no object is detected, then considering the sensor is stationary, what can be said about the movement of the object if the output by the sensor is 1010101?

• a) Object is stationary

• b) Object is oscillating side by side

• c) Object is continuously moving away

• d) Object is continuously moving closer