Tropical Year

-
The definition of the tropical year
 

The tropical year is defined as the time interval between two successive passages of the earth through the vernal equinox, which takes place approximately on March 21st  each year. It may also be defined as 1/86,400 of the mean solar day, which is the time interval between two successive passages of a point on the earth in front of the sun average over one year.
But this definition has the drawback that, because of tidal action the period of earth's rotation is decreasing gradually, and therefore this unit should also be changing gradually.

Comments

Post a Comment

Popular posts from this blog

How many Balmer series lines are in the visible part of the spectrum?

-
  Qu. How many Balmer series lines are in the visible part of the spectrum? Answer: The Balmer series or Balmer Lines are one of the sets of six named series which describe the spectral line emission of the hydrogen atom. The Balmer series is characterized by the electron making the transition from  n ≥ 3   t o   n = 2 . Where n is principal quantum number of the electron. The visible spectrum of light from hydrogen displays 4 wavelengths, 410 nm, 434 nm, 486 nm, and 656 nm. These wavelengths are corresponding to the emission of photons by electrons in excited making the transition to the quantum level having principal quantum number n=2. Therefore, 4 Balmer series lines are in the visible part of the spectrum.
Read more

Units of Measurement

-
Image
Units What are the Units? The laws of physics require  measurement and comparison of physical quantities for their description. ▪ Just like, If we need to know that whether “Alex” is heavy or   “Clay”. ▪ In that case, we will have to measure the mass of Alex and Clay. ▪ But for the measurement of their masses, we need units such as kg, pound, etc. ▪ Thus, the physical quantities are quantitatively expressed in terms of a unit of that quantity. Who decides the Units? ▪ A body named General Conference on Weight and measures (also known as CGPM) has been given the authority to decide the units by international agreement. ▪ In 1971, CGPM held it’s meeting and decided a system of units which is known as the International System of units. ▪ This system is known as S.I. system and this is widely used throughout the world. What are the types of units? Types of the units are basically, Fundamental Units and Derived Units depending on Quantity. Basically, There are two types of Qu
Read more