Which of the following rays are not electromagnetic waves?
β-rays
Heat rays
X-rays
Y-rays
The structure of solids is investigated by using
Cosmic rays
Radio waves
Infrared radiations
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
Mapping of the radio emissions from extra-terrestrial sources is known as ________________.
Radiography
Radio-astronomy
Seiesmography
None of these
In a plane electromagnetic wave, the electric field oscillates with a frequency of 2 × 1010 s-1 and an amplitude of 40 Vm-1. The wavelength of the wave is
3 × 10-3 m
2.5 × 10-2 m
1.5 × 10-2 m
4.5 × 10-3 m
Which of the following is the longest wave?
Microwaves
Radiowaves
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
What is the cause of "Green house effect"?
Infrared rays
Ultraviolet rays
Radio-waves
The frequency of y-rays, X-rays and ultraviolet rays are a, b and c respectively. Then
a > b > c
a < b < c
a = b = c
a > c > b
Which one of the following electromagnetic radiations have the smallest wavelength?
Ultraviolet waves
