29/03/2020Direct Sensing(Senior Class Physics Study by Topics) 0Comments by Gate Academy Welcome to your Direct Sensing(Senior Class Physics Study by Topics) NAME EMAIL PHONE NUMBER 1. The following are true except? MOVs are used to regulate the AC line voltage if it becomes too high. None of the above MOVs are an advanced type of Varistor. Varistors are voltage dependent resistors. MOVs are used to protect computers and electronics from surge voltages called spikes.2. Piezoelectric transducer is used for measuring chemical quantities non-electrical quantities any quantity electrical quantities3. Electromagnetic waves are defined to behave in the same way of which of the following waves? Compressional waves Transverse waves Mechanical wave Longitudinal waves4. Piezoelectric transducer consists of _________ gold crystal copper rod quartz crystal aluminum wire5. What is photogrammetry? Estimating the three-dimensional coordinates of points on an object Determining the geometric properties of objects from photographic images Optical illusion of depth created from flat, two-dimensional image or images Analysing a real-world object or environment to collect data on its shape and possibly its appearance6. Pressure measuring device consisting of a group of wires that stretch when pressure is applied. Strain gauge transducer Capacitance transducer Differential pressure cell Manometer7. Piezoelectric crystals produce _________ low voltage very high voltage no voltage high voltage8. The following are SI units of pressure except Pascal Joules N/m2 Bars9. Generally speaking, transmitters are ___________. Thermocouples Differential pressure transmitters Out dated Transducers10. Which of the following remote sensing technologies use sound? SONAR LORAN RADAR Colour Infrared11. What does temperature coefficient mean? Change in temperature How much the resistance, voltage or current of a device changes with heat or cold. For a thermistor it is the amount of resistance change The temperature at which the device has zero ohms. How hot the device can get before damage occurs.12. Instrument used to measure the difference between two pressure points Strain gauge transducer Differential pressure cell Manometer Capacitance transducer13. When a compressive force is applied to a quartz crystal positive charges are induced no charge is induced negative charges are induced both positive and negative charges are induced14. To apply pressure to an object, the force should be applied in a ___________ direction to the surface Perpendicular Vertical Horizontal None of the above15. The process of dividing pixel values in an image into a specified number of classes is called Image rectification Supervised classification Change detection Unsupervised classification16. In a strain gauge transducer, __________ flows through the wires, resistance changes proportionally to the stress or strain applied Current Pressure Electrical temperature Power17. The photoconductive cell has an increase in conduction when exposed to photon energy (light) which releases free electrons. The extra free electrons lowers the resistance of the cell allowing more current flow. False True18. The following are true except All of the above Photoconductive cells are faster than photo diodes. All optical sensors are low current devices (uA or mA). Photoconductive cells are simple to use and will work in AC or DC, photo diodes only work in a DC circuit.19. Which of the following types of electronic devices have MOVs in the power supply to protect the sensitive semiconductors from voltage spikes? Your microwave oven. All of the above Your cell phone charger. All electronic devices that operate from an AC power source20. At the start of the 19th century, how were pigeons used in the early form of remote sensing? They were used to test tracking equipment They conveyed messages from remote sensing stations to another They carried pictures from the battlefield to remote sensing stations They carried cameras which automatically took pictures21. Microphone converts light into heat. False True22. _________ is the most common measurement scale for a manometer. Vacuum manometer Bourbon tube manometer Pressure gauge manometer U-tube manometer23. The following are ways in which photoconductive (photo-resistors) are used except? Light meters Temperature detectors Motion detectors ecurity lights, the photoconductive cell is in series with a relay coil to control the current flow to the lamp.24. Which of the types of waves below has the longest wavelength? X-Rays Gamma Rays Hertzian Waves Radio Waves25. What materials are reed relays made of ? None of the above Ferrous metals Non ferrous metals Insulators26 out of 25Time is Up!