As we know that $$\mu = E \times B = {E_0}\hat i + {B_0}\hat j$$
$$E \times B$$  points in the direction of wave propagation.

Infrared radiations reflected by low lying clouds and keeps the earth warm.

The speed of light
$$C = \frac{1}{{\sqrt {{\mu _0}{\varepsilon _0}} }} = \frac{1}{{\sqrt {2 \times 8} }} = \frac{1}{4} = 0.25$$

Due to high penetrating power of X-rays, X-rays are used for investigation of structure of solids. Lane spot method and rotating cylinder method are used for this purpose. X-rays fall on solid under investigation and their structure is received on photographic plate.

Refractive index of medium is given by
$$\eqalign{ & n = \sqrt {{\mu _r}{\varepsilon _r}} . \cr & {\text{Here,}}\,\,\mu = {\mu _0}{\mu _r} \Rightarrow {\mu _r} = \frac{\mu }{{{\mu _0}}} \cr & {\text{and }}\varepsilon = {\varepsilon _0}{\varepsilon _r} \Rightarrow {\varepsilon _r} = \frac{\varepsilon }{{{\varepsilon _0}}} \cr & \therefore n = \sqrt {\frac{\mu }{{{\mu _0}}} \cdot \frac{\varepsilon }{{{\varepsilon _0}}}} = \sqrt {\frac{{\varepsilon \mu }}{{{\varepsilon _0}{\mu _0}}}} \cr} $$

Audible waves are not electromagnetic wave.

Size of particle of any wave is given in terms of wavelength
$$\eqalign{ & \lambda = \frac{c}{\nu } \cr & {\text{Here,}}\,\,\lambda = 3 \times {10^{ - 4}}cm, \cr & {\text{Velocity of light in vacuum,}}\,c = 3 \times {10^{10}}cm/s \cr & \therefore 3 \times {10^{ - 4}} = \frac{{3 \times {{10}^{10}}}}{\nu } \cr & \therefore {\text{Frequency of electromagnetic wave}}\,\nu = {10^{14}}\,Hz \cr} $$

As $$B \propto r,$$  since the point is on the axis where $$r = 0,$$   So $$B = 0$$

Wave impedance $$ = Z = \sqrt {\frac{{{\mu _0}}}{{{\varepsilon _0}}}} = 376.6\,\Omega $$

A particle is known that an electric charge at rest has electric field in the region around it, but no magnetic field. A moving charge produces both the electric and magnetic fields. If a charge is moving with a constant velocity, the electric and magnetic fields will not change with time, hence no $$EM$$ wave will be produced. But if the charge is moving with a non-zero acceleration, both the electric and magnetic field will change with space and time, it then produces $$EM$$ wave. This shows that accelerated charge emits electromagnetic waves.