Electricity and Magnetism Answers

A horizontal, straight wire carrying 12.0 A current from west to east is in the earth’s
magnetic field B. At this place, B is parallel to the surface of the earth, points to the
north and its magnitude is 0.04 mT. Determine the magnetic force on 1 m length of
the wire. If mass of this length of wire is 50 g, calculate the value of current in the
wire so that its weight is balanced by the magnetic force.

Two circular coils made of similar wire of radius 0.20m & 0.40m are connected in parallel to a battery.
Calculate the ratio of magnetic field at the centre.

lease help me ,, Three neutral spheres, electrically insulated from the environment, are touching each other as shown in the picture below. A positively charged glass rod approaches the spheres, as shown, causing them to move apart from each other. The 3 spheres separate while the rod is close, but never touching any sphere.

After the rod is put away, the spheres stay charged on the following manner:

a) 2 positively charged and one negatively charged

b) 2 neutral and 1 positive

c) 1 neutral, 1 positive, 1 negative

d) 2 neutral and 1 negative

is transformer a ohmic or non ohmic device?

what is the total electric force on -2nC charge? q4=-4nC, q2=-2nC, q7=7nC, the distance between q2 and q4 is 0.12mm and the distance between q4 and q7 is 0.05mm.

3 Which of the following is NOT correct?
Electric charge cannot be produced by frictional forces
Electric charge is conserved
Electric charges are integral multiple of the electronic charge
induced charges are the result of charge separation within a material

4 Which of the following is not true of an electrostatic force?
it acts along the line joining the point charges
it obeys an inverse square law
it is mutually attractive or repulsive
it is weaker than the gravitational attraction between the charged particles.

5 A tiny ball of mass 0.60 g is suspended from a rigid support with a piece of thread in a horizontal electric field of intensity 700 N/C. The ball is in equilibrium when the thread is inclined at an angle of
20o
to the vertical. What are the magnitude and sign of the charge on the ball? Take
g=9.8m/s2
−3.1×10−6C
3.2×10−6C
4.2×10−6C
−4.1×10−3

Explain with the help of diagrams what spherically and cylindrically symmetric
charge distributions are. What is the electric field at a point inside a hollow metallic
sphere of radius R having volume charge densityρ?

Different materials transmit or reflect wifi signals to differing degrees. What is happening within the materials at an atomic level, to cause the different behavior? Why do materials with high dielectric constant tend to reflect wifi signals, while low dielectric materials allow wifi to pass through?

Q: Derive an expression for divergence E ( divE) for a point inside and outside of a charge distribution?

a) If we rub two bodies together, so that one becomes +vely charge & the other -vely. does this mean that CHARGES (electron) moved from +vely charge body to -vely charge body?
b) If it is the case then after some time they lose their property of interaction(repulsion,attraction) . Where does these charges go?