Which one of the following statements is wrong ?
Radio waves in the frequency range 30 MHz to 60 MHz are called sky waves.
Radio horizon of the transmitting antenna for space wave is (R = radius of earth, hT = height of transmitting antenna)
Within the skip distance neither the ground waves nor the sky waves are received
The principle of fibre optical communication is total internal reflection
A plane electromagnetic wave travels in free space along x-axis. At a particular point in space, the electric field along y-axis is 9.3 Vm-1. The magnetic induction is
3.1 × 10-8 T
3 × 10-5 T
3 × 10-6 T
9.3 × 10-6 T
The dielectric constant of air is 1.006. The speed of electromagnetic wave travelling in air is a x 108 ms-1, where a is about
3
3.88
2.5
3.2
A.
3
For an electromagnetic wave (in vacuum),
Velocity,
Air acts almost as vaccum, hence
a = 3 (approx)
Of the above statements
A and B are true
B and C are true
A and D are true
A and C are true
The frequency of X-rays, γ-rays and ultraviolet rays are respectively a, b and c then
a < b, b > c
a > b, b > c
a > b, b < c
a < b, b < c
Velocity of electromagnetic waves in a medium depends upon
thermal properties of medium
mechanical and electrical properties of medium
electrical and magnetic properties of the medium
mechanical and magnetic properties of the medium
In the electromagnetic spectrum, the visible spectrum lies between
radiowaves and microwaves
infrared and ultraviolet rays
microwaves and infrared spectrum
X-ray and γ-ray spectrum
Maxwell in his famous equation of electromagnetism introduced the concept
AC current
DC current
displacement current
impedance
Out of the following electromagnetic radiations, which has the shortest wavelength ?
Radiowaves
Infrared
X-rays
Visible light