NEET News

### Which radiations are used in tratement of muscles ache?

Which radiations are used in tratement of muscles ache?

Options

(a) Ultraviolet (b) Infrared (c) Microwave (d) x-rays

Infrared

Explanation:

Infrared rays are used in physical therapy.

### An electromagnetic wave of frequency v = 3.0 MHz passes from vacuum into

An electromagnetic wave of frequency v = 3.0 MHz passes from vacuum into a dielectric medium with relative permittivity ε = 4.0. Then

Options

(a) wavelength is doubled and frequency is unchanged (b) […]

### The ratio of amplitude of magnetic field to the amplitude of electric field for

The ratio of amplitude of magnetic field to the amplitude of electric field for an electromagnetic wave propagating in vacuum is equal to:

Options

(a) The speed of light in vacuum (b) reciprocal […]

### The electric field associated with an e.m. wave in vacuum is given by

The electric field associated with an e.m. wave in vacuum is given by E = i 40 cos (kz – 6 x 10⁸ t), where E, z and t are in volt/m, meter and seconds […]

### The decreasing order of wavelength of infrared, microwave, ultraviolet and gamma

The decreasing order of wavelength of infrared, microwave, ultraviolet and gamma rays is

Options

(a) microwave, infrared, ultraviolet, gamma rays (b) gamma rays, ultraviolet, infrared, microwaves (c) microwaves, gamma rays, infrared, ultraviolet (d) […]

### The electric and magnetic field assiciated with an E.M. wave

The electric and magnetic field associated with an E.M. wave, propagating along the +z axis, can be represented by

Options

(a) [ E = E₀i, B = B₀j ] (b) [E = E₀k, […]

### which of the following statement is false for the properties of electromagnetic waves?

which of the following statement is false for the properties of electromagnetic waves?

Options

(a) Both electric and magnetic field vectors attain the maxima and minima at the same place and same time. […]

### The electric field part of an electromagnetic wave in a medium is represented by

The electric field part of an electromagnetic wave in a medium is represented by Ex = 0 Ey = 2.5 (N / C) cos [(2π x 10⁶ rad/m) t – (π x 10⁻² rad/s) x […]

### If c is the velocity of light in free space, the time taken by light to travel

If c is the velocity of light in free space, the time taken by light to travel a distance x in a medium refractive index μ is

Options

(a) x/c (b) μx/c (c) […]

### The velocity of electromagnetic radiation in a medium of permittivity ε₀

The velocity of electromagnetic radiation in a medium of permittivity ε₀ and permeability μ₀ is given by

Options

(a) √(ε₀ / μ₀) (b) √(μ₀ ε₀) (c) 1 / √(μ₀ ε₀) (d) √(μ₀ / ε₀)

1 2 3