a point source of light is placed at the center of curvature of a hemispherical surface. radius r&inner surface is totally reflecting.find force on the hemisphere due 2 lightfalling on it if source emits power wMY APPROACHENERGY EMITED by source in 4pie solid angle per sec = Wfor hemisphere solid angle=2pieso, energy falling/sec on hemisphere =(w/4pie)*(2pie)=w/2momentum=e/c=w/2cas the surface is reflecting so total momentumchange=2*(w/2c)=w/cHOWEVER THE ANSER IS GIVEN W/2C IN H.C.VERMA2 PG NO.360 QN NO.6TELL HOWI THINK H.C.VERMA HAS WRONGLY WRITEN THE AREA AS 4(pie)R(square) it should be 2 instead of 4

Amit Saxena , 11 Years ago

Grade upto college level