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)
Ozone layer blocks the radiations of wave length
less than 3 × 10-7 m
equal to 3 × 10-7 m
more than 3 × 10-7 m
all of the above
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
Electromagnetic waves are
transverse waves
longitudinal waves
produced by charges moving with constant velocity
none of the above
Which one of the following electromagnetic radiations have the smallest wavelength?
X-rays
y-rays
Ultraviolet waves
Microwaves
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
Which of the following rays are not electromagnetic waves?
β-rays
Heat rays
What is the cause of "Green house effect"?
Infrared rays
Ultraviolet rays
Radio-waves
If λv, λx and λm represent the wavelengths of visible light, X-rays and microwaves respectively, then
λm > λx > λv
λv > λm > λx
λm > λv > λx
λv > λx > λm
The frequency of electromagnetic wave, which is best suited to observe a particle of radius 3 × 10-4 cm, is of the order of
1015
1014
1013
1012
