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In electric fields, D= ε E. The correct expression which is analogous in magnetic fields will be
b Explanation: In electric fields, the flux density is a product of permittivity and field intensity. Similarly, for magnetic fields, the magnetic flux density is the product of permeability and magnetic field intensity, given by B= μ H.
b
See lessExplanation: In electric fields, the flux density is a product of permittivity and field
intensity. Similarly, for magnetic fields, the magnetic flux density is the product of
permeability and magnetic field intensity, given by B= μ H.
Find the current in a conductor with resistance 2 ohm, electric field 2 units and distance 100cm.
a Explanation: We know that E = V/d. To get potential, V = E X d = 2 X 1 = 2 volts. From Ohm’s law, V = IR and current I = V/R = 2/2 = 1A.
a
See lessExplanation: We know that E = V/d. To get potential, V = E X d = 2 X 1 = 2 volts. From Ohm’s law, V = IR and current I = V/R = 2/2 = 1A.
Find the current density of a material with resistivity 20 units and electric field intensity 2000 units.
d Explanation: The current density is given by J = σ E, where σ is the conductivity. Thus resistivity ρ = 1/σ. J = E/ρ = 2000/20 = 100 units.
d
See lessExplanation: The current density is given by J = σ E, where σ is the conductivity. Thus
resistivity ρ = 1/σ. J = E/ρ = 2000/20 = 100 units.
Find the inductance of a coil with permeability 3.5, turns 100 and length 2m. Assume the area to be thrice the length.
: a Explanation: The inductance is given by L = μ N2A/l, where μ= μoμr is the permeability of air and the material respectively. N = 100 and Area = 3 X 2 = 6. L = 4π X 10-7 X 1002 X 6/2 = 131.94mH.
: a
See lessExplanation: The inductance is given by L = μ N2A/l, where μ= μoμr is the permeability of air and the material respectively. N = 100 and Area = 3 X 2 = 6. L = 4π X 10-7 X 1002 X 6/2 = 131.94mH.
Find the inductance of a coil with permeability 3.5, turns 100 and length 2m. Assume the area to be thrice the length.
a Explanation: The inductance is given by L = μ N2A/l, where μ= μoμr is the permeability of air and the material respectively. N = 100 and Area = 3 X 2 = 6. L = 4π X 10-7 X 1002 X 6/2 = 131.94mH.
a
See lessExplanation: The inductance is given by L = μ N2A/l, where μ= μoμr is the permeability of air and the material respectively. N = 100 and Area = 3 X 2 = 6. L = 4π X 10-7 X 1002 X 6/2 = 131.94mH.
The resistance of a material with conductivity 2millimho/m2 , length 10m and area 50m is
c Explanation: The resistance is given by, R = ρL/A, where ρ is the resistivity, the inverse of conductivity. R = 10/(0.002 X 50) = 100 ohm.
c
See lessExplanation: The resistance is given by, R = ρL/A, where ρ is the resistivity, the inverse of conductivity. R = 10/(0.002 X 50) = 100 ohm.
Calculate the capacitance of a material in air with area 20 units and distance between plates is 5m.
a Explanation: The capacitance of any material is given by, C = εA/d, where ε = εoεr is the permittivity in air and the material respectively. Thus C = 1 X 8.854 X 10-12 X 20/5 = 35.36pF.
a
See lessExplanation: The capacitance of any material is given by, C = εA/d, where ε = εoεr is the permittivity in air and the material respectively. Thus C = 1 X 8.854 X 10-12 X 20/5 =
35.36pF.
Find the force experienced by an electromagnetic wave in a conductor?
d Explanation: The electromagnetic wave experiences Lorentz force which is the combination of the electrostatic force and magneto static force. It is given by F = QE + Q(V X B).
d
See lessExplanation: The electromagnetic wave experiences Lorentz force which is the
combination of the electrostatic force and magneto static force. It is given by F = QE +
Q(V X B).
Find the magnetic field when the magnetic vector potential is a unit vector.
c Explanation: We know that H = -Grad(V), where is a unit vector. The gradient of a constant/unit vector will be zero. Thus the magnetic field intensity will be zero.
c
See lessExplanation: We know that H = -Grad(V), where is a unit vector. The gradient of a
constant/unit vector will be zero. Thus the magnetic field intensity will be zero.
Choose the best relation.
c Explanation: For any magnetic field, the magnetic field intensity will be the negative gradient of the potential of the field. This is given by H = -Grad(V).
c
See lessExplanation: For any magnetic field, the magnetic field intensity will be the negative
gradient of the potential of the field. This is given by H = -Grad(V).