Question

A Review A 4.2 cm x 3.5 cm rectangle lies in the ry-plane. You may want to review (Pages 664 - 668) Part A What is the electric flux through the rectangle if Ē - (1002 - 220K) N/C? % Ad 0 2 ? N-m/C Submit Previous Answers Request Answer X Incorrect; Try Again; 5 attempts remaining

Answer 1

The area of the plate is

A = 4.2cm x 3.5cm = 0.042m x 0.035m = 1.47 x 10-3 m2

The direction of area vector of the rectangle is normal to the xy-plane in which the rectangle lies. Their is an ambiguity in the direction of area vector, it can either be taken as the positive z-direction ($\hat k$) or as the negative z-direction ($-\hat k$). The area vector can be either

Ā= AŘ or Ā= A(-k)

The electric flux in uniform electric field is

Q = Ē. A

Q = (100 î – 220 Â) · (A(+)) Nm²/C

Q = (100 î – 220 Â) · (+1.47 x 10–3 k) Nm²/C

Q = (-220) x (+1.47 x 10-3) Nm10

Q = 70.3234 Nm2/C

The electric flux will be negative if we choose the direction of area vector to be in the positive z-direction, the electric flux will be positive if we choose the direction of area vector to be in the negative z-direction.

You can try first the negative value and then the positive value.