A person walking on a road observed some water being present on the road but when he go there actually he did not find any water. What is that actually formed is called ? Explain that process.

c) A diver under water, looks obliquely at a fisherman standing on the bank of a lake. Would the fisherman look taller or shorter to the diver than what he actually is ?

Nikith and Vamsi are friends. They are walking on tar road at the afternoon time. Vamsi has seen that images of water on roads. He has shown it to Nikith, Vamis asked Nikith to guess the reasons for the shades of water. If you were asked the same what will you guess ?

A man walks on a straight road from his home to a market 2.5 km away with a speed of 5km h^-1 . Finding the market closed, he instantly turns and walks back home with a speed of 7.5 km h^-1 . What is the (a) magnitude of average velocity and (n) average speed of the man over the time interval 0 to 50 minutes?

When we concept that one mole of a substance contains the same numbers of elementary entities or one mole of any other substance, we don’t actually need to know what that number is. Sometimes however we will need to work with the actual number of elementary entities in a mole of substance. This number is called Avogadro.s number. N_(A)=6.022137xx10^(23) molecules The unit mol^(-1) which we read as per mole signifies that a collection of N_(A) molecular level entities is equivalent to one mole at the macroscopic level. For example a mole of carbon contains 6.02xx10^(23) atoms of C. A mole of oxygen gas contains 6.02xx10^(23) molecules of O_(2) . The number of atoms present in 8 g of ozone is

The only electron in the hydrogen atom resides under ordinary conditions on the first orbit. When energy is supplied, the electron moves to higher energy orbit depending on the amount of energy absorbed. When this electron returns to any of the lower orbits, it emits energy. Lyman series is formed when the electron returns to the lowest orbit while Balmer series is formed when the electron returns to second orbit. Similarly, Paschen, Brackett and Pfund series are formed when electron returns to the third, fourth orbits from higher energy orbits respectively (as shown in figure) Maximum number of lines produced when an electron jumps from nth level to ground level is equal to (n(n-1))/(2) . For example, in the case of n = 4, number of lines produced is 6. (4 rarr 3, 4 rarr 2, 4 rarr 1, 3 rarr 2, 3 rarr 1, 2 rarr 1) . When an electron returns from n_(2) to n_(1) state, the number of lines in the spectrum will be equal to ((n_(2) - n_(1))(n_(2)-n_(1) +1))/(2) If the electron comes back from energy level having energy E_(2) to energy level having energy E_(2) then the difference may be expressed in terms of energy of photon as E_(2) - E_(1) = Delta E, lambda = (h c)/(Delta E) . Since h and c are constant, Delta E corresponds to definite energy, thus each transition from one energy level to another will prouce a higher of definite wavelength. THis is actually observed as a line in the spectrum of hydrogen atom. Wave number of the line is given by the formula bar(v) = RZ^(2)((1)/(n_(1)^(2)) - (1)/(n_(2)^(2))) Where R is a Rydberg constant (R = 1.1 xx 10^(7)) (i) First line of a series : it is called .line of logest wavelength. or .line of shortest energy.. (ii) Series limit of last of a series : It is the line of shortest wavelength or line of highest energy. The difference in the wavelength of the 2^(nd) line of Lyman series and last line of Bracket series in a hydrogen sample is