Electricity and Magnetism Answers

A small 10 mm diameter permanent magnet produces a field of 100 mT. The field drops away rapidly with

distance and is negligible more than 1 mm from the surface. If this magnet moves at a speed of 1 m/s through a 100-turn coil of length 1 mm and diameter just larger than the magnet, what is the EMF induced?

A coil of wire of 20 turns has across sectional area of 0.1 m2. A magnetic field of 0.5T passes through the coil

parallel to the plane of the coil. What is the total magnetic flux through the coil?

Two point charges are placed as follows: charge q1 = -1.50 nC is at y = +6.00 m and charge q2 = +3.20 nC is at the origin. What is the total force (magnitude and direction) exerted by these two charges on a negative point charge q3 = -5.00 nC located at (2.00 m, -4.00 m)?

A very large, superconducting solenoid such as one used in MRI scans, stores 1.00 MJ of energy in its magnetic field when 100 A flows. (a) Find its self-inductance. (b) If the coils

“go normal,” they gain resistance and start to dissipate thermal energy. What temperature increase is produced if all the stored energy goes into heating the 1000 kg magnet,

given its average specific heat is 200 J/kg·oC ?

1. Compute for the amount of charge (q) of a 15 V battery with -45 J potential energy

2. A metal sphere has 5x10^-9C static charge. Compute the voltage if the radius is equal to 0.05m. (k=8.99 x 10^9 N.m^2/C^2

3. Find the Total capacitance of the three given capacitors in series connection, given their

individual capacitances, 4.0 μF, 15.0 μF.

4. Find the net capacitance of the three given capacitors connected in parallel, given their individual capacitances, 2.0 μF, 5.0, μF, 8.0 μF.

5. A parallel plate capacitor was placed 0.002 m apart. Compute for the capacitance if the area each plate is equal to 0.025 m^2. (ε0 = 8.85x10^-12 F/m)

Two point charges are placed as follows: charge q1 = -1.50 nC is at y = +6.00 m and charge q2 = +3.20 nC is at the origin. What is the total force (magnitude and direction) exerted by these two charges on a negative point charge q3 = -5.00 nC located at (2.00 m, -4.00 m)?

A parallel-plate air capacitor is to store charge of magnitude 240.0 pC on each plate when the

potential difference between the plates is 42.0 V. (a) If the area of each plate is 6.80 cm2

, what is

the separation between the plates? (b) If the separation between the two plates is double the value

calculated in part (a), what potential difference is required for the capacitor to store charge of

magnitude 240.0 pC on each plate?

The plates of a parallel-plate capacitor are 2.50 mm apart, and each carries a charge of

magnitude 80.0 nC. The plates are in vacuum. The electric field between the plates has a magnitude

of 4.00 X 106 V/m(a) What is the potential difference between the plates? (b) What is the area of

each plate? (c) What is the capacitance?

A thin spherical shell with radius R1 = 3.00 cm is concentric with a larger thin spherical shell

with radius R2 = 5.00 cm. Both shells are made of insulating material. The smaller shell has

charge q1 = +6.00 nC distributed uniformly over its surface, and the larger shell has charge

q2 = - 9.00 nC distributed uniformly over its surface. Take the electric potential to be zero at an

infinite distance from both shells. (a) What is the electric potential due to the two shells at the

following distance from their common center: (i) r = 0; (ii) r = 4.00 cm ; (iii) r = 6.00 cm? (b) What

is the magnitude of the potential difference between the surfaces of the two shells? Which shell is

at higher potential: the inner shell or the outer shell?

A small particle has charge – 5.00 µC and mass 2.00 X 10-4 kg. It moves from point A, where

the electric potential is VA = +2.00 V, to point B, where the electric potential is VB = +8.00 V. The

electric force is the only force acting on the particle. The particle has speed 5.00 m/s at point A.

What is its speed at point B? Is it moving faster or slower at B than at A? Explain.