Electromagnetic theory miscellaneous


Electromagnetic theory miscellaneous

Electromagnetic Theory

  1. Consider two fields
    E = 120 π cos (106 πt – βx) ay V/m
    and H = A cos (106 πt – βx) az A/m
    The values of A and β which will satisfy the Maxwell's equation in a linear isotropic homogeneous lossless medium with εr = 8 and µr = 2 will be—
    A (in A/m)β (in rad/m)
    A. 10.0105
    B. 10.042
    C. 20.0105
    D. 20.042










  1. View Hint View Answer Discuss in Forum

    We know that

    η =
    μ
    =
    μrμ0
    εεrε0

    we get →H =
    → E
    → E
    η120 π

    →H = cos (106πt − β X)az
    →H = A cos (106πt − β X)
    A =
    120 π
    η

    =
    120 π
    μrμ0
    εrε0

    =
    120
    μr
    (120π)
    ε0

    A =
    εr
    μr

    =
    8
    = 2
    2

    for the lossless homogeneous medium phase velocity =
    ω
    β

    given, ω = 106 π
    v =
    106π
    and v =
    c
    βμrεr

    =
    3 × 108
    16

    ∴    β =
    4 × 106 × π

    4 × π
    = 0.042
    3 × 108300

    Correct Option: D

    We know that

    η =
    μ
    =
    μrμ0
    εεrε0

    we get →H =
    → E
    → E
    η120 π

    →H = cos (106πt − β X)az
    →H = A cos (106πt − β X)
    A =
    120 π
    η

    =
    120 π
    μrμ0
    εrε0

    =
    120
    μr
    (120π)
    ε0

    A =
    εr
    μr

    =
    8
    = 2
    2

    for the lossless homogeneous medium phase velocity =
    ω
    β

    given, ω = 106 π
    v =
    106π
    and v =
    c
    βμrεr

    =
    3 × 108
    16

    ∴    β =
    4 × 106 × π

    4 × π
    = 0.042
    3 × 108300