A new unit of length is chosen such that the speed of light in vacuum is unity. What is the distance between the Sun and the Earth in terms of the new unit if light takes 8 min and 20 s to cover this distance?

In Young's double slit experiment using light of wavelength 5000Å, the fringe width is 0.6 cm. If the distance between the slit abd screen is reduced to half , calculate the new fringe width.

A LASER is a source- of very intense, monochromatic, and unidirectional beam of light. These properties of a laser light can be exploited to measure long distances. The distance of the Moon from the Earth has been already determined very precisely using a laser as a source 'of light. A laser light beamed at the Moon takes 2.56 s to return after reflection at the Moon’s surface. How much is the radius of the lunar orbit around the Earth?

A crystal of lead (Ii) sulphide has fcc structure. In this crystal the shortest distance between a Pb^(2+) ion and a S^(2-) ion is 297pm. What is the length of the unit cell is lead sulphide? Also Calculate the unit cell volume (N_A=6.023xx10^23 mol^-1, Pb=297.2u, S=42 u)

Two trains A and B of length 400 m each are moving on two parallel tracks with a uniform speed of 72 km h^-1 in the same direction, with A ahead of B. The driver of B decides to overtake A and accelerates by 1 m//s^-2 . If after 50 s, the guard of B just brushes past the driver of A, what was the original distance between them?

A rocket is fired from the earth towards the sun. At what distance form the earth's centre is the gravitational force on the rocket zero? Mass of the sun = 2 xx 10^20 kg and mass of earth = 6 xx 10^24 kg and orbital radius 1.5 xx 10^-8 km.

A calorie is a unit of heat or energy and it equals about 4.2 J where 1J = 1 kg m^2s^(-2)c . Suppose we employ a system of units in which the unit of mass equals a kg, the unit of length equals R m, the unit of time y s? Show that a calorie has a magnitude 4.2 a^(-1) beta(-2) gamma2 in terms of the new units.

The nearest star to our solar system is 4.29 light years away. How much is this distance in terms of parsecs? How much parallax would this star (named Alpha Centauri) show ,when viewed from two locations of the Earth six months apart* in its orbit around the Sun?