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In an electromagnet as the electric current changes what happens to the magnetic field?
the magnetic field would constantly change, that's why the AC current is converted to DC current
Why a current wire deflects a magnetic needle placed near it?
A current wire deflects a magnetic needle placed near it because the current wire is creating an electric field. If the current is supplied from an AC (alternating current source as opposed to DC which is direct current- AC would be from a wall socket, DC from a battery), then the current is constantly changing, so the electric field is constantly changing. A changing electric field results in a magnetic field perpendicular (90 degrees) to it. It is actually the magnetic field that is changing the needle direction, because that needle is trying to follow the magnetic field lines (similar to those that you see when you put iron filing near a magnet).
What does a inductor do in a circuit?
DC current has no effect on the inductor(can be considered as a short circuit) as the current does not change in a DC supply voltage this one just produces a magnetic field which remains constant , as the magnetic field is not varying no emf is induced in the circuit , so literally it has no effect on the circuit when the supply is of DC voltage.when an alternating current is set up in a circuit , the Alternating current brings a magnetic field in the inductor which is variable (since the current is varying...) this variable magnetic field induces an emf in the circuit (back emf) which opposes the cause that is producing the change (lenz's law)explanation consider a circuit with an inductor connected to an AC voltageduring the positive half cycle when the voltage increases the current also increases in the circuit [take the current direction as clockwise] this causes a variable increasing magnetic field in the inductor , this magnetic field in turn induces current in the circuit which is opposing the increase in the current flow from the original source, the inverse happen during the decreasing half of the half of the positive cycle , here the induced current adds up with the decreasing current opposing the cause that produced this back current (cause :- decrease in current changes the magnetic field so the induced current is produced ..... it is opposing the change because :- the induced current either decreases the increasing current or increases the decreasing current )
How can you use a solenoid to make a temporal magnet?
Passing it through a coil that has a DC current through it. The DC current creates a field which allows the realignment of electrons in the solenoid, allowing it to have temporary magnetic properties. Passing an AC current through the coil would demagnetize the solenoid.
How do you produce a uniform magnetic field?
To make a long story short I wanna mention the name of several methods to make uniform dc magnetic fields: Using the space inside a solenoid Using the Helmholtz coil Using the Maxwell coil as all of these configurations take benefits of the phenomena in which current produces a magnetic field, the amplitude of the magnetic field would be easily controlled by control upon the current passes the loops of windings.
What is the effect of field current on dc motor?
The field current of a dc motor provides the magnetic field that allows the motor to develop a torque when current flows through the armature..
In an electromagnet as the electric current changes what happens to the magnetic field?
the magnetic field would constantly change, that's why the AC current is converted to DC current
Is electromagnetism is possible with AC?
AC current creates an alternating magnetic field, consistent with the alternating voltage. The only way I know of using AC current to create a constant magnetic field is to rectify the AC into DC and then use that DC to create the magnetic field.
Why is dc current used in the excitation of generator?
The field current is used for the excitation of generators.AnswerYou use DC current, because you want the resulting magnetic field to be constant. If you used AC, the resulting magnetic field would vary in both strength and direction.
Can a dc electric field produce magnetic field?
Yes. A steady current will produce a magnetic field, B= uI/r
Can DC be used for transformer?
Basis of transformer is change in current. Whenever current flows it causes magnetic field. Current flow in primary coil causes magnetic field around secondary. Since current is changing as in the case of AC, magnetic filed also changes. As per Faraday's law change in magnetic field causes induced voltage at secondary coil. In case of DC there wont be any change in current, thus no change in magnetic field leading to no induced voltage.
Why doesn't a transformer work only on a DC supplyand not in ac supply?
A transformer doesn' t work with DC current because voltage is induced in the output winding of the transformer when a magnetic field passes through the coils of this winding. This happens with AC current because the magnetic field is continually expanding and contracting. With a DC current the magnetic field is unchanging other than when you first turn it on. Since the magnetic field is not moving it is not moving through the windings and no voltage is produced.
Armature reaction in a DC generator?
ARMATURE REACTION in DC MachineAll current-carrying conductors produce magnetic fields. The magnetic field produced by current in the armature of a dc generator affects the flux pattern and distorts the main field. This distortion causes a shift in the neutral plane, which affects commutation. This change in the neutral plane and the reaction of the magnetic field is called armature reaction.
What is the function of field winding in DC generator?
The motor needs the current and magnetic flux to create motion The magnetic field is created by field winding where as armature carries the current resulting into the rotation of armature
DC current is not used in transformer?
No. Transformers rely on the magnetic field changing direction to work, so DC can't be used.
Why a current wire deflects a magnetic needle placed near it?
A current wire deflects a magnetic needle placed near it because the current wire is creating an electric field. If the current is supplied from an AC (alternating current source as opposed to DC which is direct current- AC would be from a wall socket, DC from a battery), then the current is constantly changing, so the electric field is constantly changing. A changing electric field results in a magnetic field perpendicular (90 degrees) to it. It is actually the magnetic field that is changing the needle direction, because that needle is trying to follow the magnetic field lines (similar to those that you see when you put iron filing near a magnet).
What is armature in motors?
The armature has the stationary (not physically moving) magnetic field, which attracts the magnetic field in the rotor. Since DC does not alternate, a split ring is used to alternate the current (and resulting magnetic field), so that the rotor will spin.
