Electromagnetic waves propagate much differently in conductors than they do in dielectrics or in vacuum. If the resistivity of the conductor is sufficiently low (that is, if it is a sufficiently good conductor), the oscillating electric field of the wave gives rise to an oscillating conduction current that is much larger than the displacement current. In this case, the wave equation for an electric field:

Del(ρ/ε₀) - (Del)²E = -dμ₀J/dt

Explanation:

From Maxwell's fourth equation

Curl B = μ₀J + μ₀ε₀dE/dt (1) where the second term is the displacement current.

If the oscillation conduction current in the conductor is much larger than the displacement current then, the displacement current goes to zero. So we have

Curl B = μ₀J  (2)(since μ₀ε₀dE/dt = 0)

From maxwell's third equation

Curl E = -dB/dt  (3)  

taking curl of the above from the left

Curl(Curl E) = Curl(-dB/dt)

Curl(Curl E) = (-d(CurlB)/dt)  (4)

Substituting for Curl B into (4), we have

Curl(Curl E) = -dμ₀J/dt

Del(DivE) - (Del)²E = -dμ₀J/dt    (5)

From Maxwell's first equation,

DivE = ρ/ε₀

Substituting this into (5), we have

Del(ρ/ε₀) - (Del)²E = -dμ₀J/dt

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =