This question was previously asked in

GATE EC 2014 Official Paper: Shift 2

Option 2 : E = -2ŷ, H = -3ẑ

ISRO Scientist ECE: 2020 Official Paper

349

80 Questions
240 Marks
90 Mins

__Concept__:

A TEM wave traveling in the given direction must satisfy the Poynting theorem, as it describes the magnitude and direction of the flow of energy in electromagnetic waves.

Mathematically, the Poynting vector is the cross-product of the Electric field vector and the magnetic field vector, i.e.

\(P = \vec E × \vec H\;Watt/{m^2}\)

__Analysis__:

**Option 1:**

With E = +8 ŷ and H = -4 ẑ

According to Poynting theorem, the direction of propagation will be:

P̅ = 8 ŷ × (-4ẑ)

P̅ = - 32 x̂

Since the direction of propagation given is +x direction, Option 1 is incorrect.

Option 2:

With E = -2ŷ and H = -3ẑ

P̅ = -2ŷ × (-3ẑ)

P̅ = 6 x̂

**Since the direction of propagation given is +x direction, Option 2 is correct.**

Option 3:

With E = +2ẑ and H = +2ŷ

P̅ = 2ẑ × (2ŷ)

P̅ = - 4 x̂

Since the direction of propagation given is +x direction, Option 3 is incorrect.

Option 4:

With E = -3ŷ and H = +4ẑ

P̅ = -3ŷ × (4ẑ)

P̅ = - 12 x̂

Since the direction of propagation given is +x direction, Option 4 is incorrect.