Consider the following two statements regarding a linearly polari… - Vidyadip

MCQ

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

The electric field and the magnetic field have equal average values.
The electric energy and the magnetic energy have equal average values.

A
Both $A$ and $B$ are true.
B
$A$ is false but $B$ is true.
✓
$B$ is false but $A$ is true
D
Both $A$ and $B$ are false.

✓

Answer

Correct option: C.

$B$ is false but $A$ is true

For a linearly polarised, plane electromagnetic wave,
$\text{E}=\text{E}_0\sin\omega\Big(\text{t}-\frac{\text{x}}{\text{c}}\Big)$
$\text{B}=\text{B}_0\sin\omega\Big(\text{t}-\frac{\text{x}}{\text{c}}\Big)$
The average value of either $E$ or Bover a cycle is zero $($average of $\sin(\theta)$ over a cycle is zero$).$
Also the electric energy density $(U_E)$ and magnetic energy density $(U_B)$ are equal.
$\text{u}_\text{E}=\frac{1}{2}\in_0\text{E}^2=\frac{\text{B}^2}{2\mu_0}=\text{u}_\text{B}$
Energy can be found out by integrating energy density over the entire volume of full space.
As the energy of the electromagnetic wave is equally shared between electric and magnetic field so their average values will also be equal.

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free

Explore more

More "M.C.Q (1 Marks)" from Electromagnetic Waves→Electromagnetic Waves — all question types→Physics STD 12 Science question papers→Rajasthan Board STD 12 Science question papers→Rajasthan Board question paper generator→

Similar questions

A luminous object is placed at a distance of 30 cm from the convex lens of focal length 20 cm. On the other side of the lens, at what distance from the lens a convex mirror of radius of curvature 10 cm be placed in order to have an upright image of the object coincident with it(a) 12 cm(b) 30 cm(c) 50 cm(d) 60 cm

The equivalent resistance between points $A$ and $B$ of an infinite network of resistances each of $1 \Omega$ connected as shown, is

The magnetic field due to a current carrying circular loop of radius $3 \ cm$ at a point on the axis at a distance of $4 \ cm$ from the centre is $54 \mu T.$ What will be its value at the centre of the loop

Assertion : Newton’s rings are formed in the reflected system. When the space between the lens and the glass plate is filled with a liquid of refractive index greater than that of glass, the central spot of the pattern is dark.
Reason : The reflection is Newton’s ring cases will be from a denser to a rarer medium and the two interfering rays are reflected under similar conditions.(a) If both assertion and reason are true and the reason is the correct explanation of the assertion.(b) If both assertion and reason are true but reason is not the correct explanation of the assertion.(c) If assertion is true but reason is false.(d) If the assertion and reason both are false.

A coil having 500 square loops each of side 10 cm is placed normal to a magnetic flux which increases at the rate of 1.0 tesla/second. The induced e.m.f. in volts is(a) 0.1(b) 0.5(c) 1 (d) 5

A thin, metallic spherical shell contains a charge $Q$ on it. A point charge $q$ is placed at the centre of the shell and another charge $q_1$ is placed outside it as shown in figure. All the three charges are positive. The force on the charge at the centre is:

An achromatic combination of lenses produces(a) Coloured images(b) Highly enlarged image(c) Images in black and white(d) Images unaffected by variation of refractive index with wavelength

Imagine that you are sitting in a room with your back to one wall and that an electron beam traveling horizontally from the back wall towards the front one is deflected towards the right. What is the direction of the magnetic induction field that exists in the room?

Wave front formed by the collimator of a spectrometer:

The value of internal resistance of an ideal cell is(a) Zero(b) 0.5 Ω(c) 1 Ω(d) Infinity