Electricity and Magnetism Answers

5. A negative charge of magnitude q is placed at the origin. Two positive charges of magnitude
q are placed along the horizontal axis at L and −L.
(i) What is the net electrical force on the negative charge?

Each cubic meter of the wire contains approximately 8.5x10^28 free electrons. The diameter of the wire is 2.5 mm and the length of wire within the magnetic field is 0.15 m. Deduce the speed of the electrons in the wire when the current is 0.20 A.

A vertical rod of 1.5 m is at rest in the earths magnetic field mif it starts moving at right angle to magnetic meridian with a uniform acceleration of 5m/s^2, find instantaneous induced emf in it at the end of 2 second

When the current in the wire is 0.20 A, the magnetic field strength at the upper section of wire due to the lower section of wire is 1.3 x 10^-4 T.

Calculate the magnetic force acting per unit length on the upper section of wire.

An alternating pd of rms values 240v is applied to the terminals of an ideal transformer having 600 turns in the primary and 45 in the secondary. Across the secondary is connected a load of resistance 15ohms. Determine (a) the rms pd over the secondary (b) the rms current through the load (c) the power of the secondary circuit (d) the rms current, taken by the primary

A charge of +0.25 C is moved from a position where the electric potential is 10V to a position where it is 90V what is the change in the potential energy of the charge ?

(electrostatics).
Figure below shows a charge q1 (= +1.0 x 10-6 C) 10.0 cm from a charge q2 (= -1.0 x 10-6 C).
(a) Find the electric field strength (magnitude and direction) at point P if the distance between charge q2 and point P is 2.5 cm.
(b)Find the electric force (magnitude and direction) on a test charge of 10.0 C at P.
(Coulomb constant: k = (1/40) = 8.9875109 Nm2/ C2)

Two charges A and B are fixed in place, at different distances from a certain spot. At this spot the potentials due to the two charges are equal. Charge A is 0.19 m from the spot, while charge B is 0.67 m from it. Find the ratio qB/qA of the charges.

Three point charges, q1=+5x10-6C, q2=-8x10-6C and q3=+2x10-6C, are placed on the corners of an equilateral triangle with sides of length 120 mm. Find the magnitude and direction of the net force over charge q1=+5x10-6C (use 2 decimal plates)

A circular coil of 10 turns and diameter 12cm carries a current I. The coil is placed with its plane in the magnetic meridian of the earth. A small, magnetic needle placed at the center of the coil makes 30 oscillations per minute about a vertical axis. When the current is cut off, it makes 15 revolutions per minute. If the horizontal component of the earth’s magnetic flux density is 2.0 x 10-5 T, calculate the magnitude of the current I. (Assume that the square of frequency of oscillations is proportional to the magnetic flux density)