The structure of solids is investigated by using
cosmic rays
X-rays
y-rays
infrared radiations
If a source is transmitting electromagnetic waves of frequency 8.2 × 106 Hz, then wavelength of the electromagnetic waves transmitted from the source will be
40.5 m
42.3 m
36.6 m
50.9 m
What is the cause of "Green house effect"?
Infrared rays
Ultraviolet rays
Radio-waves
The velocity of electromagnetic radiation in a medium of permittivity ε0 and permeability μ0 is given by
A signal emitted by an antenna from a certain point can be received at another point of the surface in the form of
sky wave
ground wave
sea wave
both (a) and (b)
Which of the following rays are not electromagnetic waves?
β-rays
Heat rays
A TV tower has a height of 100 m. How much population is covered by the TV broadcast if the average population density around the tower is 1000 km-2 (radius of earth = 6370 km)?
4 lakh
40,000
4000
40 lakh
The velocity of electromagnetic wave is along the direction of
In a certain region of space electric file and magnetic field are perpendicular to each other and an electron enters in region perpendicular to the direction of and both and moves undeflected, then velocity of electron is
The charging current for a capacitor at any instant is 0.25 A.The displacement current across the capacitor plates at that instant is
0.5 A
0.25 A
2.5 A
1 A
