Electricity and Magnetism Answers

What is superconductor

Three charges were present inside the wire. Charge #1 has 3.2c, charge #2 has 4.1c, and charge #3 has -2.9c. Each charge has a distance of 8m to each other.

a. What is the total force between charges #1 and #2?

b. What is the total force between charges #2 and #3?

c. What is the total force and direction of the charges assuming that our charge #1 is the starting point? 

Write down the Maxwell equation in SI unit

A long solenoid of cross-sectional area 28𝑐𝑚2

A coil 𝐶 of 160 turns of insulated wire is wound tightly around the centre of the solenoid. If 𝑛 is a 

constant equal to 1.5 × 10

3𝑚−1

and 𝜇𝑜 is the permeability of free space, calculate for a current of 

3.5𝐴 in the solenoid; (i) the magnetic flux at the centre of the solenoid. (ii) the flux linkage in the 

coil 𝐶. (iii) If the current in the coil 𝐶 is reversed in 0.80𝑠, calculate the average e.m.f. induced in 

the coil 𝐶.

. A conductor of length 𝐿 moves at a steady speed vat right angles to a uniform magnetic field 

of flux density 𝐵. Show that the e.m.f. 𝐸 across the ends of the conductor is given by the 

equation 𝐸 = 𝐵𝑙𝑣.

Find the diameter of a copper wire which has the same resistance as aluminium wire of equal 

length and diameter 1.20mm. The resistivities of copper and aluminium at room temperature are 

1.7 × 10^−8Ω𝑚 and 2.6 × 10^−8Ω𝑚 respectively.

Consider two 100𝜇𝐹 capacitors. One is charged to 10V, disconnected from the power supply, 

and then connected across the other. Calculate the energy stored by the combination

Consider a region without charges, where the electric field lines inside this region are all continuous and parallel. Is it possible to find two points with different electric field intensity E? Use fundamental properties of electric fields to make your argument.

 Two concentric conducting spheres are filled with an insulating material of uniform charge density ρ0. The inner sphere has radius ra and is held at a potential φ0. The outer sphere has a radius rb and is grounded. (a) Determine the potential and field everywhere in space. (b) What is the capacitance of this object?

A sphere of charge Q and radius R has an electric field 𝐸(𝑟) = 𝑟4𝐸𝑚𝑎𝑥/𝑅4 for r ≤ R. (a) Find the charge density of the sphere as a function of r. (b) Find the potential function in all space for this object. Give your answers in terms of Q, R, and r.