Question

The flux crossing the three symmetric faces which are close to the point charge will be if point charge is just outside of the cube

• A. $\frac{q}{8{\epsilon }_0}$
• B. $\frac{q}{{\epsilon }_0}$
• C. $\frac{7q}{8{\epsilon }_0}$
• D. $\frac{q}{6{\epsilon }_0}$

Answer 1

The correct option is A $\frac{q}{8{\epsilon }_0}$

Since if charge is like placed at the centre of the cube then flux linked with it will be $q/{ϵ}_o$. Now charge is placed at the corner of the cube therefore, from that point of view we can see that we can imagine that charger to be placed at the center of a large cube and the cube at whose corner the charge is placed is 1/8th part of the larger cube. Therefore, flux linked with the larger cube will be $q/{ϵ}_o$ therefore, flux linked with the smaller cube will be $q/8{ϵ}_o$ Now if charge is placed just outside the cube at one corner of the cube then also we can assume that charge is placed at the corner but this time flux linked with the three symmetric surfaces which are closer to charge is not zero. It is also $q/8{ϵ}_o$

Option(A)