Question

In: Physics

When a DC current passes through the coil, it will produce a magnetic flux around the...

When a DC current passes through the coil, it will produce a magnetic flux around the coil. Is this the reason why the coil get heated? Because the magnetic flux will be stable after all as DC current does not oscillate?

Solutions

Expert Solution

For a coil V=L di/dt is the voltage equation.since there is no change of current in DC ,di/dt=0 except during the transient period.Then V=0.This means short circuit.So high currents will flow and burn out the winding. it can also be explained in another way.

for a coil Z=R+jωL. ω= 2*pi*f,For DC f=0,so ω=0 ,Z=R.For a coil L will be more and R will be less.So Z will be very less and very high currents will flow and damage the circuit.

If we neglect the proper impedance of the wire, the theoretical impedance of the coil is proportional to the frequency : Zcoil = j.L.ω with ω = 2.π.f and L the inductance of the coil.

If the current is DC then f = 0 and consequently Zcoil = 0, the coil acts only as a wire.

Obviously the wire has a little impedance that should be taken in account if necessary, according to your needs. It can cause some Joule losses for example, depending on the cross section of the wire and the current value.

Supposes a coil is there. Initially the switch of the circuit is off. So, no current passing through it. Now at some time "t", you trigger the switch ON. So from current=0A the coil now faces a sudden change of current through it. Thus, for a moment flux is generated through the coil and it opposes the current initially. But as this is DC, flux generated remain just for a fraction of a second(called Transient period) and then the coil allows the passage of DC Current.

So, in short COIL ACTS AS AN OPEN CIRCUIT FOR TRANSIENT PERIOD AND THEN AS SHORT CIRCUIT WHEN A DC FLOWS THROUGH IT.


Related Solutions

What is the magnetic flux through a square wire loop with 2m sides when it is...
What is the magnetic flux through a square wire loop with 2m sides when it is placed within a 3T uniform magnetic field that is perpendicular to the surface of the wire loop?
If the magnitude of \(\vec{B}\) increases while its direction remains unchanged, how will the magnetic flux through the coil change?
If the magnitude of \(\vec{B}\) increases while its direction remains unchanged, how will the magnetic flux through the coil change? Check all that apply. The flux is unchanged because the position of the coil with respect to \(\vec{B}\) unchanged. The flux increases because the magnitude of \(\vec{B}\) increases. The flux decreases because the magnitude of \(\vec{B}\) increases. The flux is unchanged because the surface area of the coil is unchanged.
If the magnet moves as shown in the diagram, the primary flux through the coil
1) If the magnet moves as shown in the diagram, the primary flux through the coil A. increases and points to the right. B. increases and points to the left. C. decreases and points to the right. D. decreases and points to the left.   2) The magnetic flux is changing as it passes through two coils that are exactly the same. The induced voltage is greatest in the coil whose flux is changing fastest. True False   3) The...
Use a diagram to illustrate the flow of magnetic flux around a transformer. Draw an equivalent...
Use a diagram to illustrate the flow of magnetic flux around a transformer. Draw an equivalent circuit for this transformer and explain how it relates to the practical transformer.
1- A magnet created when there is a current through a coil of wire is considered...
1- A magnet created when there is a current through a coil of wire is considered a. electromagnet. b. a solenoid. c. polarized. d. all of the above 2- The radii of the paths that ions follow in a mass spectrometer can be used to calculate the charge on the ion. a. True b. False 3- The __________ difference between two points separated by a distance d in a uniform field is represented by the equation ΔV = Ed. a....
The magnetic flux through a 10.0-cm2cm2 loop is 8.0 T⋅cm2T⋅cm2, and the magnetic field at the...
The magnetic flux through a 10.0-cm2cm2 loop is 8.0 T⋅cm2T⋅cm2, and the magnetic field at the location of the loop is uniform. Choose all correct answers. Check all that apply. A)If BB = 1.0 TT, then the angle between the B⃗ B→ field and the normal to the loop's surface is greater than 0∘∘. B)If the direction of B⃗ B→ field is parallel to the normal to the loop's surface, then BB = 0.8 T. C)The magnitude of the B⃗...
a) How does the magnetic flux through the loop changes as the magnet rotates. Is the...
a) How does the magnetic flux through the loop changes as the magnet rotates. Is the flux maximal when the magnet is horizontal or vertical on the screen? Why? b) How does changing the magnetic flux works to create an emf (potential difference) in the coil, which alternates over time (use the Faraday’s law equation)?
The magnetic dipole moment (μ) of a coil depends on the current (I), the area of...
The magnetic dipole moment (μ) of a coil depends on the current (I), the area of the coil (A), and the number of loops (N). Rank the three different coils of wire shown figure below in order by the magnitude of their magnetic dipole moment. Rank the coils from greatest to least magnetic dipole moment. If the coils have the same magnetic dipole moment, place them on top of each other.
is the torque on a current carrying coil in a uniform magnetic field always zero?
is the torque on a current carrying coil in a uniform magnetic field always zero?
when the current[ =Ⅰ ] flowing through the wire in the direction of the z-axis, magnetic...
when the current[ =Ⅰ ] flowing through the wire in the direction of the z-axis, magnetic vector potential is following that A = ez[μⅠ*ln(1/ρ)/2π] show that magnetic field B is same as B = eφ[μI/2πρ]
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT