Electricity and Magnetism Answers

A long straight wire of radius R carries a steady current I. The current is uniformly distributed over its cross section. The magnetic field at a distance 2a/3 from its centre is

An object which is 6.0 cm tall is situated 20 cm from a converging lens of 15 cm focal length. Determine the position and nature of the image

An object 6 cm high is located in front of a convex spherical mirror of radius 40 cm. Determine the position and the nature of the image.

A microscope is sharply focused on a mark. When a parallel plate of glass 4.8 mm thick is placed over the mark, the microscope has to be raised 0.18 cm to refocus. What is the refractive index of the glass?

A charge Q is uniformly distributed throughout a sphere of radius a. Taking the potential at infinity as zero, the potential at r = b < a is

A potential field is given by V = 3x^2y - yz. Which of the following is not true?

(a) At point (1, 0, -1) V and E vanish.

(b) x^2y = 1 is an equipotential line on the xy-plane.

(c) The equipotential surface V = - 8 passes through point P + 2, -1, 4)

(d) The electric field at P is 12ax - 8ay - az V/m.

(e) A unit normal to the equipotential surface V = - 8 at P is -0,83ax + 0,55ay+ 0,07az.

The work done by the force F = 4ax - 3ay + 2az N in giving a 1 nC charge a displacement of 10ax + 2ay - 7az m is

Point charges 30 nC, - 20 nC, and 10 nC are located at (-1, 0, 2), (0, 0, 0) and (1, 5, -1) respectively. The total flux leaving a cube of side 6 m centered at the origin is

Suppose a uniform electric field exists in the room in which you are working, such that the lines of force are horizontal and at right angles to one wall. As you walk toward the wall from which the lines of force emerge into the room, are you walking toward

(a) points of higher potential?

(b) points of lower potential?

(c) points of the same potential (equipotential line)?