The true value of dip at a place is `30^(@)` . The vertical plane carrying needle is turned through `30^(@)` from magnetic meridian . Calculate apparent value of angle of dip .

Explanation

`tan delta_(A) = ( tan delta )/(cos alpha)`
`tan delta_(A) = (tan 30^(@))/(cos 30^(@))`
`= ((1)/(sqrt3))/((sqrt3)/(2))`
`tan delta_(A) = (2)/(3)`
`delta_(A) = tan^(-1)((2)/(3))`