MCQ
An electromagnetic wave propagating along north has its electric field vector upwards. Its magnetic field vector point towards.
- ANorth
- BEast
- CWest
- DDownwards
✓
Answer
- East
Explanation:
Electric field and magnetic field vectors for an electromagnetic wave are cross - field vectors.
So, the direction of an electromagnetic wave is given by the product of electric field vector and magnetic field vector.
According to the question, electric field vector is directed upwards and EM wave is directed towards North. So, according to the right - hand thumb rule, the magnetic field vector points towards the East.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
A photo cell is receiving light from a source placed at a distance of 1 m. If the same source is to be placed at a distance of 2 m, then the ejected electron
|
(a) Moves with one-fourth energy as that of the initial energy |
|
(b) Moves with one-fourth of momentum as that of the initial momentum |
|
(c) Will be half in number |
|
(d) Will be one-fourth in number |
A microscope is focussed on a coin lying at the bottom of a beaker. The microscope is now raised up by 1 cm. To what depth should the water be poured into the beaker so that coin is again in focus ? (Refractive index of water is 
)
|
(a) 1 cm |
(b) |
(c) 3 cm |
(d) 4 cm |
The slope of plate characteristic of a vacuum diode is 2 
The plate resistance of diode will be
|
(a) 50 W |
(b) 50 kW |
(c) 500 kW |
(d) 500 kW |
Which one of the following statements is correct
|
(a) In vacuum, the speed of light depends upon frequency |
|
(b) In vacuum, the speed of light does not depend upon frequency |
|
(c) In vacuum, the speed of light is independent of frequency and wavelength |
|
(d) In vacuum, the speed of light depends upon wavelength |
Light of wavelength 1824 Å, incident on the surface of a metal, produces photo-electrons with maximum energy 5.3 eV. When light of wavelength 1216 Å is used, the maximum energy of photoelectrons is 8.7 eV. The work function of the metal surface is
|
(a) 3.5 eV |
(b) 13.6 eV |
(c) 6.8 eV |
(d) 1.5 eV |
The magnetic induction at a point P which is distant 4 cm from a long current carrying wire is 
. The field of induction at a distance 12 cm from the same current would be
|
(a) 3.33 |
(b) 1.11 |
(c) 3 |
(d) 9 |
Calculate the surface integral of a magnetic field over a surface.
The grid in a triode valve is used
|
(a) To increases the thermionic emission |
|
(b) To control the plate to cathode current |
|
(c) To reduce the inter-electrode capacity |
|
(d) To keep cathode at constant potential |
Magnitude of produced magnetic field at any point inside a solenoid depends on:
Which can pass through 20 cm thickness of the steel
|
(a) α - particles |
(b) β - particles |
(c) γ- rays |
(d) Ultraviolet rays |