Find density of ethyl alcohol

Explanation

Consider two small elements subtending angle `d theta` at centre symmetrically at angle `theta` with symmetry line. Electric field due to each of them
`dE'=(1)/(4piepsilon_(0))(lambdaRd theta)/(R^(2))=(1)/(4piepsilon_(0))(lambda)/(R)d theta`
Net field due to both the symmetrical elements `dE=2dE'costheta`
`E=intdE=underset(0)overset(phi//2)int2(1)/(4piepsilon_(0))(lambda)/(R)costhetad theta=(1)/(4piepsilon_(0))(2lambda)/(R)sin((phi)/(2))`