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The energy in a magnetic material is due to which process?
b Explanation: The energy in a magnetic material is due to the formation of magnetic dipoles which are held together due to magnetic force. This gives energy to the material. Hence it is due to magnetization process.
b
See lessExplanation: The energy in a magnetic material is due to the formation of magnetic
dipoles which are held together due to magnetic force. This gives energy to the material. Hence it is due to magnetization process.
The induced emf in a material opposes the flux producing it. This is
c Explanation: The induced emf in a material under the influence of a magnetic field will oppose the flux that produces it. This is indicated by a negative sign in the emf equation. This phenomenon is called Lenz law.
c
See lessExplanation: The induced emf in a material under the influence of a magnetic field will oppose the flux that produces it. This is indicated by a negative sign in the emf equation. This phenomenon is called Lenz law.
The magnetic energy of a magnetic material is given by
a Explanation: The magnetic energy of a material is given by half of the product of the magnetic flux density and the magnetic field intensity. It is represented as BH/2. Since B= μH, we can also write as μH2 or B2/2μ.
a
See lessExplanation: The magnetic energy of a material is given by half of the product of the
magnetic flux density and the magnetic field intensity. It is represented as BH/2. Since B= μH, we can also write as μH2 or B2/2μ.
The inductance of a coaxial cable with inner radius a and outer radius b, from a distance d, is given by
a Explanation: The inductance of a coaxial cable with inner radius a and outer radius b, from a distance d, is a standard formula derived from the definition of the inductance. This is given by L = μd ln(b/a)/2π.
a
See lessExplanation: The inductance of a coaxial cable with inner radius a and outer radius b,
from a distance d, is a standard formula derived from the definition of the inductance.
This is given by L = μd ln(b/a)/2π.
Find the inductance of a coil with turns 50, flux 3 units and a current of 0.5A
b Explanation: The self inductance of a coil is given by L = Nφ/I, where N = 50, φ = 3 and I= 0.5. Thus L = 50 x 3/0.5 = 300 units.
b
See lessExplanation: The self inductance of a coil is given by L = Nφ/I, where N = 50, φ = 3 and I= 0.5. Thus L = 50 x 3/0.5 = 300 units.
Calculate the mutual inductance of two tightly coupled coils with inductances 49H and 9H.
a Explanation: For tightly coupled coils, the coefficient of coupling is unity. Then the mutual inductance will be M = √(L1 x L2)= √(49 x 9) = 21 units.
a
See lessExplanation: For tightly coupled coils, the coefficient of coupling is unity. Then the
mutual inductance will be M = √(L1 x L2)= √(49 x 9) = 21 units.
The inductance is proportional to the ratio of flux to current. State True/False.
a Explanation: The expression is given by L = Ndφ/di. It can be seen that L is proportional to the ratio of flux to current. Thus the statement is true.
a
See lessExplanation: The expression is given by L = Ndφ/di. It can be seen that L is proportional to the ratio of flux to current. Thus the statement is true.
With unity coupling, the mutual inductance will be
c Explanation: The expression for mutual inductance is given by M = k √(L1 x L2), where k is the coefficient of coupling. For unity coupling, k = 1, then M = √(L1 x L2).
c
See lessExplanation: The expression for mutual inductance is given by M = k √(L1 x L2), where k is the coefficient of coupling. For unity coupling, k = 1, then M = √(L1 x L2).
A coil is said to be loosely coupled with which of the following conditions?
d Explanation: k is the coefficient of coupling. It lies between 0 and 1. For loosely coupled coil, the coefficient of coupling will be very less. Thus the condition K<0.5 is true.
d
See lessExplanation: k is the coefficient of coupling. It lies between 0 and 1. For loosely coupled coil, the coefficient of coupling will be very less. Thus the condition K<0.5 is true.
The equivalent inductance of two coils with series opposing flux having inductances 7H and 2H with a mutual inductance of 1H.
b Explanation: The equivalent inductance of two coils in series with opposing flux is L = L1+ L2 – 2M, where L1 and L2 are the self inductances and M is the mutual inductance. Thus L = 7 + 2 – 2(1) = 7H.
b
See lessExplanation: The equivalent inductance of two coils in series with opposing flux is L = L1+ L2 – 2M, where L1 and L2 are the self inductances and M is the mutual inductance. Thus L = 7 + 2 – 2(1) = 7H.