Class 11th

The height 'h' at which the weight of a body will be the same as that at the same depth 'h' from the surface of the earth is (Radius of the earth is R and effect of the rotation of the earth is neglected)

Let S be the sum of the first 9 terms of series (x+ka)+(x²+(k+2)a)+(x³+(k+4)a)+(x?+(k+6)a)+., where a≠0 and x≠1. If S=(x¹?-x+45a(x-1))/(x-1), then k is equal to

In a hydrogen atom, an electron makes a transition from (n + 1)th level to the nth level. If n >> 1, the frequency of radiation emitted is proportional to:

In the following, digital circuit, what will be the output at ' Z ', when the input (A, B) are (1,0), (0,0), (1,1), (0,1)

A charge Q is distributed over two concentric conducting thin spherical shells of radii r and R (R > r). If the surface charge densities on the two shells are equal, the electric potential at the common centre is:

An ideal gas in a closed container is slowly heated. As its temperature increases, which of the following statements are true?
(a) the mean free path of the molecules decreases
(b) the mean collision time between the molecules decreases.
(c) the mean free path remains unchanged.
(d) the mean collision time remains unchanged.

A particle is moving 5 times as fast as an electron. The ratio of the de-Broglie wavelength of the particle to that of the electron is 1.878 * 10⁻⁴. The mass of the particle is close to:

A satellite is moving in a low nearly circular orbit around the earth. Its radius is roughly equal to that of the earth's radius Rₑ. By firing rockets attached to it, its speed is instantaneously increased in the direction of its motion so that it become √(3/2) times larger. Due to this the farthest distance from the centre of the earth that the satellite reaches is R. Value of R is: