Question

When a piece of paper is held with one face perpendicular to a uniform electric field the flux through it is 25 N .m2 /C. When the paper is turned 25° with respect to the field the flux through it is:

Answer 1

Given:

Initial flux when paper was perpendicular to field is 25 Nm². Now paper is 25° with respect to field.

To find:

New flux ?

Calculation:

• Equation of initial flux is :

$\phi1 = E.S \cos( {0}^{ \circ} ) = 25 \: N { m}^{2} /C$

• Now, paper plane is turned 25° to field, hence the area vector turns by (90°-25°) = 65°

Now, flux is :

$\phi2= E.S \cos( {65}^{ \circ} )$

$\implies \phi2= E.S \times 0.42$

$\implies \phi2= \phi1 \times 0.42$

$\implies \phi2= 25 \times 0.42$

$\implies \phi2= 10.56 \: N {m}^{2} /C$

So, new flux is 10.56 Nm²/C.