Which of the statements are correct (indicate with a C) and which are incorrect (indicate with an I)? a) The hollow cube to the right is imaginary and is only there to conceal a region of space. The lines represent electric fields. Based on the figure shown there may be a positive charge inside the box as long as there is greater negative charge inside. b) For the arrangement of charges shown to the right the electric potential energy must be less than zero. c) The net magnetic flux through a closed surface that encloses the part of the north pole of a bar magnet must he less than the total flux through the same surface if it were to enclose the entire bar magnet. d) For the arrangement of charges shown to the right, the only location where the electric potential is zero is infinitely far away. e) A conducting loop that is four times wider than it is tall is in a finite region of magnetic field as shown. Initially 1/4 of the loop is in the field. As the loop is rotated about its center 90 degree counterclockwise, a clockwise current is induced in the loop.
a) is incorrect : electric field lines moves away from positive charge and towards negative charge. according to the figure, there must be some negative charge inside the box according to the direction of lines.
b) is correct : electric potential is a scaler quantity but it includes the sign of the charges. So, the net potential will be negative, means attractive potential.
c is incorrect : according to Gauss\' law, the net magnetic flux of an enclosed surface is zero.
d is incorrect : the arrangement is of a dipole. According to the formula of potential, it is zero along every point on the central verical line of the syatem.
e is correct : according to Lenz\'s law, the polarity of the induced emf is such that it produces a current whose magnetic field opposes the change which produces it.
Homework Sourse
