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by Devinalukita
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Current-carrying conductor experiences a force when placed in a magnetic field due to the presence of a stronger field on one side of the wire as all the magnetic field linesacts in the same direction. At the other end, the combined field is weaker due to opposing magnetic field lines. A force acts on the wire from the stronger field to the weaker field.

Magnetic field pattern of a solenoid resembles that of a bar magnet hence it has two poles and can be used as elctromagnet.The magnetic field lines inside the solenoid are closer together than the field lones outside which means that it is stronger than the magnetic field outside.To increase magnetic field strength of a solenoid, we can increase the current, number ofturns per unit length of the solenoid, or placing a soft iron core within the solenoid.

Circuit BreakerIt is a safety device that switches off the electrical supply when there is excessive current flow. When there is sudden surge in current, the solenoid becomes a strong solenoid and attracts the soft iron latch, releasing the spring which pushes the safety bar outwards. The interrupt point is now open and the circuit is switched off.

Oersted's experimentshows that a current-carrying conductor produces a magnetic field around it.Magnetic Field PatternMagnetic field consisted of concentric circle. The closer the circles are to one another implies that the magnetic field is stronger at the regions. The strength of the magnetic field around the wire depends on the distance from the wire. Right-hand grip rule: Direction of the curl of fingers indicates whether the magnetic field is clockwise or anticlockwise, while the direction of the thumb points the direction of current flow.When the direction of current is reversed, the direction of the magnetic field of a current-carrying wire is reversed.When the magnitude of current is increased, the strength of magnetic field of a current-carrying wire increases. The strength of the magnetic field of a flat coil can be increased by increasing the current flowing through the coil.

Magnetic Effect of a Current

Electromagnetismby: Devina :)

Currents in opposite directions cause repulsion while that in similar directions cause attraction.Forces between two parallel current-carrying conductorsWhen a beam of positive charges enter the magnetic field region, it is deflected upwards in a circular path as the moving charges experience a force perpendicular to its direction of motion while a beam of negative charges is vice versa.

Force on a current-carrying conductorThe motor effect occurs when a current-carrying conductor is placed in a magnetic field, causing the conductor to experience a force. The force acting on the current-carrying wire placed in a magnetic field is perpendicular to both the direction of the current and the direcion of the magnetic field.

D.C. MotorIt converts electrical energy into kinetic energy. It consists of rectangular coil connected in series to a battery and rheostat, permanent magnets, split-ring commutator, and two carbon brushes. Usin flemming's laft-hand rule, it is concluded that downward force acts on wire AB and upward force acts on wire CD. The coil rotates anticlockwise until it reaches vertical position.When the coil is in vertical position, the current is cut off as the split ring commutator is not in contact with the carbon brushes. The momentum of the coil carries it past the vertical position. The direction of the currents flowing through wire section AB and CD is now reversed. An upward force now acts on CD. The coil continues to rotate in anticlockwise direction.

Fleming's left hand rule:Point the thumb, forefinger and second finger at right angles to one another. The force, current and magnetic field are at right angles to one another. Thumb, forefinger and second finger signify motion, magnetic field and current respectively.

The direction of the force on a beam of charged particles is reversed when we reverse the direction of the magnetic field

Turning Effect on a Current-carrying Coil in a Magnetic FieldWhen a stiff wire coil is placed between the poles of a strong magnet and a current is passed through, a turning effect is observed. To increase the turning effect on the wire coil, we can increase the number of turns on the wire coil or increase the current in the coil.

Turning effect on current-carrying coil in d.c motor can be increased by inserting a soft iron core into the coil, number of turns in the coil or in increasing the current in the coil.


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