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Ever wondered how light travels? Or how many diagonals are present in a 100-sided polygon?!
Curious Topper readers posed these questions in Topper's Ask The Expert section, and received an answer within three working days.
Subject: Mathematics
Q. Please tell me the number of diagonals in a hundred sided polygon.
Posted by: Rakesh1994
A. For 'n' sided figure, if you join each point to every other point you will have total number of line segments given by[n(n-1)]/2]
We are dividing by 2 because line segments get repeated while counting. eg if we are counting a line segment from a point say A to another point C, then the same line segment gets counted when counting the number of line segments from C.
Also, this number contains all the sides along with the diagonals.
So the number of diagonals = total number of line segments - the number of sides = [n(n-1)/2]-n
For a quadrilateral, n = 4
So number of diagonals = [4(4-1)/2]-4 = 6-4 = 2
For a pentagon, the number of diagonals = [5(5-1)/2]-5 =10-5 = 5
Similarly, for n =100 number of diagonals = [100(100-1)]/2]-100 = 4850.
Subject: Chemistry
Q. Explain how water is purified.
Posted by: Sasha14
A. Water purification is the process of removing contaminants and other harmful micro organisms from a raw water source to make it suitable for various specific purposes like drinking and domestic consumption. There are various methods of purification of water like ultraviolet light, filtration, water softening, reverse osmosis, ultrafiltration, deionisation and powdered activated carbon treatment.
Subject: Physics
Q. How does light travels?
Posted by: Prakharabu
A. Light is made up of massless photons which are generated by the source of light in all directions. The photons carry energies equal to h (Planck's constant) times frequency. Because of this energy photons move in medium from one place to another and we say that light is moving.
Subject: Biology
Q. Energy used by a leaping frog is actually the energy obtained from the sun. Explain.
Posted by: Mohdazfar
A. Energy of all organisms is obtained from the sun. The solar energy is trapped by autotrophic organisms like green plants. They prepare their food using this energy.
This food is consumed directly or indirectly by all the other living organisms on earth, so as to obtain energy and perform various functions. Hence all actions performed by any organism including leaping of frog are obtained from the sun.
