Electricity and Magnetism Answers

The formula R = l / (sigma S) is for thin wires.

(a) True

(b) False

(c) Not necessarily

Seawater has epsilon r = 80. Its permittivity is

(a) 81

(b) 79

(c) 5.162 x 10^-10 F/m

(d) 7.074 x 10^-10 F/m

Both epsilon 0 and Xe are dimensionless.

(a) True

(b) False

If = nabla . D = epsilon nabla . E and nabla . J = sigma nabla . E in a given material, the material is said to be

(a) Linear

(b) Homogeneous

(c) Isotropic

(d) Linear and homogeneous

(e) Linear and isotropic

(f) Isotropic and homogeneous

The electric conditions (charge and potential) inside and outside an electric screening are completely independent of one another.

(a) True

(b) False

Which of the following statements are incorrect?

(a) The conductivities of conductors and insulators vary with temperature and frequency. (b) A conductor is an equipotential body in steady state, and E is always tangential to the conductor.

(c) Nonpolar molecules have no permanent dipoles.

(d) In a linear dielectric, P varies linearly with E.

What happens when a steady potential difference is applied across the ends of a conducting wire?

(a) All electrons move with a constant velocity.

(b) All electrons move with a constant acceleration.

(c) The random electronic motion will, on the average, be equivalent to a constant velocity of each electron.

(d) The random electronic motion will, on the average, be equivalent to a nonzero constant acceleration of each electron.

Which is not an example of convection current?

(a) A moving charged belt

(b) Electronic movement in a vacuum tube

(c) An electron beam in a television tube

(d) Electric current flowing in a copper wire

A 2uF capacitor is charged to 8V. It is then connected to a 12V supply and given additional charge

through a 1OMohms resistor. How long will it take to reach a voltage of 10V?