An electric dipole is formed by two equal but opposite charges , each of magnitude ` 1mu C`, separated by a distance of 5 cm. what is the magnitude of the torque required to place the dipole at right angles to an electric field of intensity ` 3 xx 10^5 N * C ^ ( - 1 ) ` ?

Explanation

Here,
`p = q xx 2l = 1 xx 10 ^( - 6 ) xx 5 xx 10 ^( - 2 ) = 5 xx 10 ^( -8 ) C * m`
` E = 3 xx 10 ^( 5 ) N* C ^ ( - 1 ) and theta = 90 ^@ `
` therefore ` The required torque,
` tau = pE sin theta = 5 xx 10 ^( -8) xx 3 xx 10 ^( 5 ) xx sin 90 ^@ `
` = 0.015 N *m`