HC Verma solutions for Concepts of Physics Vol. 2 [English] Class 11 and 12 chapter 18 - Electromagnetic Waves [Latest edition]

In a microwave oven, the food is kept in a plastic container and the microwaves 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.

A wire carries an alternating current i = i₀ sin ωt. Is there an electric field in the vicinity of the wire?

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

A plane electromagnetic wave is passing through a region. Consider (a) electric field (b) magnetic field (c) electrical energy in a small volume and (d) magnetic energy in a small volume. Construct the 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 (kx − ωt); B = B₀ sin (kx − ωt).
Which of the following equations is true?

An electric field `vec E` and a magnetic field `vec B` exist in a region. The fields are not perpendicular to each other.

Consider the following two statements regarding a linearly polarised, 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 = E₀ sin (kx − 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

(a) increases
(b) decreases
(c) does not change
(d) is zero

Speed of electromagnetic waves is the same

Which of the following have zero average value in a plane electromagnetic wave?
(a) Electric field
(b) Magnetic field
(c) Electric energy
(d) Magnetic energy

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

Show that the dimensions of the displacement current `∈_0 (d varphi_E)/dt` 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 motion of the charge. 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 of 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_dof 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"/"tau) - 1)` .

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

The sunlight reaching Earth has maximum electric field of 810 Vm⁻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 × 10¹⁵s⁻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 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.