At what height should a lamp be hung above the centre of a round table of radius R to otain the maximum illumination at its edges?

A lamp is hanging along the axis of a circular table of radius r. at what height should the lamp be placed above the table so that the intensity of illumination at the edge of the table is (1)/(8) of that at its centre ?

A lamp of 120 candela hangs at a height of 4 m excathy above the centre of a circular table of diameter of 6.m Caluclate the illuminance at the centre and at the edge of the table.

An isotropoic point source of light is suspeneded h metre vericlaly above the centre of circular table of radius r metre.Then the ratio of illumenances at the centre to that at the edge of the table is

An isotropoic point source of light is suspeneded h metre vericlaly above the centre of circular table of radius r metre.Then the ratio of illumenances at the centre to that at the edge of the table is

A small source of light is to be suspended directly above the centre of a circular table of radius R . What should be the height of the light source above the table so that the intensity of light is maximum at the edges of the table compared to any other height of the source

A student is studying a book placed near the edge of a circular table of radius R. A point source of light is suspended directly above the centre of the table. What should be the height of the source above the table so as to produce maximum illuminance at the position of the book ?