Two equal positive charges of magnitude q1 = q2 = 5 nC are on the x-axis at x1 = 0 and x2 = 4 cm.

a) What is the magnitude and direction of the electric field on the y-axis at a point P (y = 6 cm).

b) What is the magnitude and direction of the net force on test charge q0 = 1 nC placed on the y-axis at point P.

Two charges q1 = 5.5 m C and q2 = -2.5 m C are fixed in space a distance d =16 cm apart, as shown in figure below. The point C is at distance r1 = 8 cm from charge q1 and at distance r2 = 12 cm from charge q2.

a) With V = 0 at infinity, what is the electric potential at point C?

b) You bring a third charge Q = 2 m C from the infinity to C. How much work must you do?

c) What is the potential energy U of the three-charge configuration when the third charge is in place?

In circuit shown in figure below R₁ = 6W, R₂ = 4W, R₃ = 8W, R₄ = 3W, and R₅ = 7W.

1. Find the equivalent resistance of the combination.
2. If the current in resistors R₁ and R₂ is I = 1.5 A, find the emf of battery.
3. What is power dissipated in resistor R₅ ?
4. Indicate the direction (clockwise or counterclockwise) of current in this circuit?

A circular wire loop whose radius is 15 cm carries a current of 2.6 A. It is placed so that the normal to its plane makes an angle of 52o with a uniform magnetic field of 1.2 T

a) Calculate the magnetic dipole moment of the loop

b) What torque acts on the loop?

c) What torque acts on the loop when the plane of the loop is perpendicular to the magnetic field?

d) What torque acts on the loop when the plane of the loop is parallel to the magnetic field?

Two long straight parallel wires, wire 1 and wire 2, separated by 0.25 cm are perpendicular to the plane of the page as shown in figure below. Wire 1 carries a current of 12 A into the page. Consider a point P at a distance .75 cm from wire 2.

a) What must be the current (magnitude and direction) in wire 2 for the resultant magnetic field at point P to be zero?

b) What the resultant magnetic field will be if you change the direction of the current in wire 2?

The long solenoid S has 280 turns / cm and carries a current i = 2 A; its diameter is 3.2 cm. At its center we place a 130-turn close packed coil C of diameter d = 1.8 cm. The current in the solenoid S is reduced to zero at a steady rate in 25 ms.

a) What is the initial magnitude of magnetic field inside the solenoid S?

b) What is the initial flux of magnetic field through the coil C?

c) What electromotive force (emf) is induced in coil C while the current in the solenoid S is changing?