Electricity and Magnetism Answers

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)?

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

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

(b) x^2 y = 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

Point charges Q1 =1 nC and Q2 = 2 nC are at a distance apart. Which of the following statements are incorrect?

(a) The force on Q1 is repulsive.

(b) The force on Q2 is the same in magnitude as that on Q1.

(c) As the distance between them decreases, the force on Q1 increases linearly.

(d) The force on Q2 is along the line joining them.

(e) A point charge Q3 = -3 nC located at the midpoint between Q1 and Q2 experiences no net force.

The electric flux density on a spherical surface r = b is the same for a point charge Q located at the origin and for charge Q uniformly distributed on surface r = a(a < b).

(a) Yes

(b) Not necessarily

(c) No

An electric potential field is produced by point charges 1 mC and 4 mC located at (-2, 1, 5) and (1, 3, -1), respectively. The energy stored in the field is

A potential field is given by V 5 3x^2 y - yz. Which of the following is not true?

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

(b) x^2 y = 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

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

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

(b) x^2 y = 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 (2,-1,4)is a 12ax - 8ay - az

(e) none of the above

A potential field is given by V 5 3x2 y 2 yz. Which of the following is not true?

(a) At point 11, 0, 212, V and E vanish.

(b) x2 y 5 1 is an equipotential line on the xy-plane.

(c) The equipotential surface V 5 28 passes through point P+2, -1, 4

. (d) The electric field at P is 12ax 2 8ay 2 az V/m.

(e) A unit normal to the equipotential surface V 5 28 at P is 20.83ax 1 0.55ay1 0.07az.

By saying that the electrostatic field is conservative, we do not mean that

(a) It is the gradient of a scalar potential.

(b) Its circulation is identically zero.

(c) Its curl is identically zero.

(d) The work done in a closed path inside the field is zero.

(e) The potential difference between any two points is zero.

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