Calculate the electric field at point P,Q for the following two cases as shown in the figure
(a) A positive point charge +1 `muC ` is placed at the origin
(b) A negative point charge `-2 muC ` is placed at the origin

Explanation

The magnitude of the electric field at point P is
`E_(p)=(1)/(4piepsilon_(0))=(q)/(r^(2))=(9xx10^(9)xx1xx10^(-6))/(4)=2.25xx10^(3)NC^(-1)`
Since the source charge is positive the electric field points away from the charge .So electric field at the point P is given by
`vecE_(p)=2.25xx10^(3)NC^(-1)hatj`
For the point Q
`|vecE_(Q)|=(9xx10^(9)xx1xx10^(-6))/(16)=0.56xx10^(3)NC^(-1)`
Hence `vecE_(Q)=0.56xx10^(3)hatj`
Case (b) : The magnitude of the electric field at point P
`|vecE_(p)|=(kq)/(r^(2))=(1)/(4piepsilon_(0))(q)/(r^(2))=(9xx10^(9)xx2xx10^(-6))/(4)`
`=4.5xx10^(3)NC^(-1)`

Since the source charge is negative the electric field points towards the charge . So the electric field at the point P is given by
`vecE_(p)=-4.5xx10^(3)hatiNC^(-1)`
For the point Q, `|vecE_(Q)|=(9xx10^(9)xx2xx10^(-6))/(36)`
`=0.5xx10^(3)NC^(-1)`
`vecE=0.56xx10^(3)NC^(1)`
At the point Q the electric field is directed along the positive x -axis . \