In a microwave oven, the food is kept in a plastic container and the microwave is directed towards the food. The food is cooked without melting or igniting the plastic container. Explain.

A metal rod is placed along the axis of a solenoid carrying a high-frequency alternating current. It is found that the rod gets heated. Explain why the rod gets heated?

Can an electromagnetic wave be deflected by an electric field? By a magnetic field?

A wire carries an alternating current i = i₀sinωt. Is there an

electric field in the vicinity of the wire?

A capacitor is connected to an alternating-currents source. Is there a magnetic field between the plates?

Can an electromagnetic wave be polarized?

A plane electromagnetic wave is passing through a region. Consider the quantities

(a) electric field,

(b) magnetic field,

(c) electrical energy in a small volume and

(d) magnetic energy in a small volume.

Construct pairs of the quantities that oscillate with equal

frequencies.

A magnetic field can be produced by

A compass needle is placed in the gap of a parallel plate capacitor. The capacitor is connected to a battery through a resistance. The compass needle

Dimensions of 1/(μ₀ϵ₀) is

Electromagnetic waves are produced by

An electromagnetic wave going through vacuum is described by

E = E₀ sin(κx – ωt); B = B₀ sin(κx – ωt)

Then

Consider the following two statements regarding a linearly polarized, plane electromagnetic wave:

(A) The electric field and the magnetic field have equal average values.

(B) The electric energy and the magnetic energy have equal average values.

A free electron is placed in the path of a plane electromagnetic wave. The electron will start moving

A plane electromagnetic wave is incident on a material surface. The wave delivers momentum p and energy E.

An electromagnetic wave going through vacuum is described by

E = E₀sin (κx – ωt).

Which of the following is/are independent of the wavelength?

Displacement current goes through the gap between the plates of a capacitor when the charge of the capacitor

Speed of electromagnetic waves is the same

Which of the following have zero average value in a plane electromagnetic wave?

The energy contained in a small volume through which an electromagnetic wave is passing oscillates with

Show that the dimensions of the displacement current are that of an electric current.

A point charge is moving along a straight line with a constant

velocity v. Consider a small area A perpendicular to the direction of motion of the charge figure. Calculate the displacement current through the area when its distance from the charge is x. The value of x is not large so that the electric field at any instant is essentially given by Coulomb’s law.

A parallel-plate capacitor having plate-area A and plate separation

d is joined to a battery of emf ϵ and internal resistance R at t = 0.

Consider a plane surface of area A/2, parallel to the plates and

situated symmetrically between them. Find the displacement current

through this surface as a function of time.

Consider the situation of the previous problem. Define displacement resistance R_d = V/i_d of the space between the plates where V is the potential difference between the plates and i_d is the displacement current. Show that R_d varies with time as

R_d = R (e^t/τ – 1)

Using B = μ₀ H find the ratio E₀/H₀ for a plane electromagnetic wave propagating through vacuum. Show that is has the dimensions of electric resistance. This ratio is a universal constant called the impedance of free space.

The sunlight reaching the earth has maximum electric field of 810 V m^–1. What is the maximum magnetic field in this light?

The magnetic field in a plane electromagnetic wave is given by

B = (200 μT) sin [(4.0 × 10¹⁵ s^–1) (t –x/c)].

Find the maximum electric field and the average energy density corresponding to the electric field.

A laser beam has intensity 2.5 × 10¹⁴ W m^–2. Find the amplitudes of electric and magnetic fields in the beam.

The intensity of the sunlight reaching Earth is 1380 W m⁻². Assume this light to be a plane, monochromatic wave. Find the amplitudes of electric and magnetic fields in this wave.