In the original Fizeau method, the light travelled 8.6 km and then returned. What could be the difficulty if this distance is taken as 8.6 m ?

A convex lens of diameter 8.0 cm is used to focus a parallel beam of light of wavelength 620 nm. If the light be focused at a distance of 20 cm from the lens, what would be the radius of the central bright spot formed ?

The intensity of sound from a point source is 1.0 xx 10^-8 Wm^-2 , at a distance of 5.0 m from the source. What will be the intensity at a distance of 25 m from the source ?

A new unit of length is chosen such that the speed of light in vscuum 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.

A kho - kho player in a practice sesssion while running realises that the sum of the distances from the two kho-kho poles from him is always 8m. Find the equation of the path traced by him of the distances between the poles is 6m.

Find the resistance of a copper coil of total wire-length 10m and area of cross section 1.0mm^(2) . What would be the resistance of a similar coil of aluminium? The resistivity of copper =1.7xx10^(-8)(Omega)m and that of aluminium 2.6xx10^(-8)(Omega).

Two circles of radius 8.2 cm and 3.6 cm touch each other externally , the distance between their centres is …………

A train covered a certain distance at a uniform speed. If the train would have been 6 km.hr faster, it would have taken 4 hours less than the schedule time. And, if train were slower by 6 km/hr, it would have taken 6 hours more than the schedule time. Find the length of the journey.

A transmitting antenna has a height of 40 m and the height of the receiving antenna is 30 m. What is the maximum distance between them for line-of-sight communication? The radius of the earth is 6.4xx10^(6)m