A uniform field of magnitude `vec E = 2000 NC^-1` is directed `theta = 37^(@)` below the horizontal [fig. 3.11].
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(i) Find the potential difference between P and R.
(ii) If we define the reference level of potential so that potential at R is `V_R = 500 V`, what is the potential at P?

Explanation

(i) Here `E = 2000 NC^-1, theta = 37^(@), V_R = 500 V`
`Delta l = PR = 5 cm = 5 xx 10^-2 m`
`V_R - V_P = vec E . Delta vec l = - E d l cos theta`
=`-(2000 NC^-1)(5 xx 10^-2 m) cos 37^(@)`
`V_R - V_P = - 80 V`
Thus, `V_P - V_R = vec E . Delta vec l = 80 V`
(ii) As `V_P- V_R = 80 V and V_R = 500 V`,
`V_P = 500 V + 80 V = 580 V`.