Download App

Electromagnetic Waves — Physics STD 12 Science — Question

Bihar BoardEnglish MediumSTD 12 SciencePhysicsElectromagnetic Waves1 Mark
MCQ
Consider an electromagnetic wave propagating in vacuum. Choose the correct statement:
  • A
    For an electromagnetic wave propagating in +y direction the 1 A electric field is $\overrightarrow{\text{E}}=\frac{1}{\sqrt{2}}\text{E}_\text{yz}(\text{x,t})\hat{\text{z}}$ and the magnetic field is $\overrightarrow{\text{B}}=\frac{1}{\sqrt{2}}\text{B}_\text{z}(\text{x,t})\hat{\text{y}}$
  • B
    For an electromagnetic wave propagating in +y direction the electric field is $\overrightarrow{\text{E}}=\frac{1}{\sqrt{2}}\text{E}_\text{yz}(\text{x,t})\hat{\text{y}}$ and the magnetic field is $\overrightarrow{\text{B}}=\frac{1}{\sqrt{2}}\text{B}_\text{z}(\text{x,t})\hat{\text{z}}$
  • C
    For an electromagnetic wave propagating in +x direction the electric field is $\overrightarrow{\text{E}}=\frac{1}{\sqrt{2}}\text{E}_\text{yz}(\text{y,z,t})(\hat{\text{y}}+\hat{\text{z}})$ and the magnetic field is $\overrightarrow{\text{B}}=\frac{1}{\sqrt{2}}\text{E}_\text{yz}(\text{x,t})(\hat{\text{y}}+\hat{\text{z}})$
  • D
    For an electromagnetic wave propagating in +x direction the electric field is $\overrightarrow{\text{E}}=\frac{1}{\sqrt{2}}\text{E}_\text{yz}(\text{x,t})(\hat{\text{y}}-\hat{\text{z}})$ and the magnetic field is $\overrightarrow{\text{B}}=\frac{1}{\sqrt{2}}\text{E}_\text{yz}(\text{x,t})(\hat{\text{y}}+\hat{\text{z}})$
✓

Answer

  1. For an electromagnetic wave propagating in +x direction the electric field is $\overrightarrow{\text{E}}=\frac{1}{\sqrt{2}}\text{E}_\text{yz}(\text{x,t})(\hat{\text{y}}-\hat{\text{z}})$ and the magnetic field is $\overrightarrow{\text{B}}=\frac{1}{\sqrt{2}}\text{E}_\text{yz}(\text{x,t})(\hat{\text{y}}+\hat{\text{z}})$

Explanation:

Electromagnetic waves travel in the direction perpendicular to electric as well as magnetic field. Cross product of electric and magnetic field should give the direction of electromagnetic wave.

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 [1M]" from Electromagnetic Waves→Electromagnetic Waves — all question types→Physics STD 12 Science question papers→Bihar Board STD 12 Science question papers→Bihar Board question paper generator→

Similar questions

A biconvex lens of glass having refractive index 1.47 is immersed in a liquid. It becomes invisible and behaves as a plane glass plate. The refractive index of the liquid is:

→
Equipotential surfaces:
→

Two bar magnets with magnetic moments 2 M and M are fastened together at right angles to each other at their centres to form a crossed system, which can rotate freely about a vertical axis through the centre. The crossed system sets in earth’s magnetic field with magnet having magnetic moment 2M making and angle q with the magnetic meridian such that

(a) θ =  

(b) θ =   

(c) θ =   

(d) θ =   
→

Heavy water is used as moderator in a nuclear reactor. The function of the moderator is

(a) To control the energy released in the reactor

(b) To absorb neutrons and stop chain reaction

(c) To cool the reactor faster

(d) To slow down the neutrons to thermal energies
→

A deutron is bombarded on   nucleus and a-particle is emitted. The product nucleus is

(a)  

(b)  

(c)  

(d)  
→

Assertion :  Basic difference between an electric line and magnetic line of force is that former is discontinuous and the latter is continuous or endless.

Reason     : No electric lines of forces exist inside a charged body but magnetic lines do exist inside a magnet.

(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 current i ampere flows along the inner conductor of a coaxial cable and returns along the outer conductor of the cable, then the magnetic induction at any point outside the conductor at a distance r metre from the axis is

(a) ∞       

(b) Zero

(c)     

(d)  
→
An element has number of proton = 7. Then what will be its atomic number?
→
Newton's law of cooling is a special case of:
  1. Wien's displacement law.
  2. Kirchhoff's law.
  3. Stefan's law.
  4. Planck's law.
→

The magnetic potential at a point on the axial line of a bar magnet of dipole moment M is V. What is the magnetic potential due to a bar magnet of dipole moment  at the same point

(a) 4V

 (b) 2V

 (c)  

 (d)  
→