Explanation

Optical fibers transmit data as light signals.

The signal is confined within the fiber due to the phenomenon where light hits a medium boundary.

It is completely reflected back.

Explanation

The main idea of the solar system was proposed by the Polish astronomer Nicolaus Copernicus (1473-1543).

who said that "the Sun is the centre of the Universe" and made the planets move around it in perfect circles

(in his book entitled, "On the Revolution of the Celestial Spheres", written in Latin and published in 1543)

Explanation

An anemometer is an instrument that measures wind speed.

This type of anemometer has a spinning wheel.

Additional Information:

A hygrometer is an instrument used to measure humidity

A salinometer is used to measure the salinity

A bolometer is used to measure the power of incident electromagnetic radiation

A barometer is used to measure air pressure in certain environment.

Explanation

• Wavelength is the distance between two consecutive points on a wave that are in phase with each other.
• Such as two crests or two troughs.

Explanation

Short-sightedness is caused due to elongation of the eyeball

 It also may result when the curve of the cornea is too steep. 

The messages sent from the retina to the brain are perceived as blurry

Explanation

Non-renewable energy sources:

• Oil
  
• Nuclear energy
• Petroleum
• Natural gas & coal

Renewable sources of energy:

• Solar energy
• Wind energy
• Hydroelectric power
• Biomass energy
• Geothermal energy
• Tidal energy

Explanation

In the metric system, the SI unit of length is a meter which is

defined as: “The length of the path traveled by light in a vacuum within 1⁄299792458 seconds.”

Common symbols: l

ND18-9-2023

Explanation

Light year refers to speed of light expressed in miles per year

(it is about ten trillion kilometers or six trillion miles).

Light year is a unit of distance.

Light Year: the distance that light can travel in one year. 

The distance light travels in one year is known as the light year.

Explanation

Decibel (dB) is the unit used to measure sound intensity.

Which is related to the amplitude of a sound wave.

The amplitude of a sound wave determines the loudness of the sound

One decibel (0.1 bel) equals 10 times the common logarithm of the power ratio.

Explanation