Explanation

GPS is an abbreviation of Global positioning system

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The Global Positioning System, originally Navstar GPS, is a satellite-based radio navigation system owned by the United States government and operated by the United States Space Force. 

The GPS (Global Positioning System) is a "constellation" of 31 well-spaced satellites that orbit the Earth

Coverage: Global

Cost: $12 billion; (initial constellation); $750 million per year; (operating cost)

First launch: February 22, 1978; 44 years ago

Orbital height: 20,180 km (12,540 mi)

Regime(s): 6 MEO planes

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Explanation

The principal axis is a straight line passing through the center of curvature and the pole of a spherical mirror.

It serves as the reference line for measuring distances and analyzing image formation in mirrors.

Explanation

In a periscope, mirrors are placed at 45° angles to reflect light down the tube.

This allows the viewer to see over or around obstacles.

Explanation

The El Niño-Southern Oscillation (ENSO) cycle primarily occurs in the East-central Equatorial Pacific Ocean.

It involves periodic changes in sea surface temperatures and atmospheric pressures, influencing global weather patterns.

Explanation

A CT (Computed Tomography) scan uses X-rays and computer processing to create detailed cross-sectional images of the body.

It helps in diagnosing various conditions by providing more detailed images than regular X-rays.