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electric current, Magnetism, DC-CIRCUITS - Coggle Diagram
electric current
current
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Q=ne
Q=charge, e= magnitude of charge of electron
Resistivity
R=ρl /A
R=resistance, ρ =resistivity of material, l= length of material, A=cross-sectional area of material
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ohm's Law
V=IR
V=voltage, I=current, R=resistance
conductivity
σ=1/ρ
where σ=conductivity of material, ρ= resistivity of material
current density
J=I/A
J=σE
J=current density, σ=conductivity of material, E=magnitude of electric field , I=electric current, A=area of cross-section of material
J=nqe
where, J=current density, n=number of electrons per unit volume, e= magnitude of charge of electron
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power
P=VI, P=V^2/R,P=RI^2
Where, P=power, I=current, R=resistance,V=potential difference/voltage
Magnetism
Hall effect
Whenever we place a current carrying conductor in a magnetic field, there is a deflection of the charge carriers due influence of magnetic field in the conductor body.
halls voltage
Vh=IB/(nxe)
where Vh=halls voltage,I=current through conductor, B=magnitude of magnetic field, n=number of electrons per unit volume, x=thickness of conductor, e=magnitude of charge of electron
Mainly Lorentz force is responsible for Hall effect. All of we know that when we place a current carrying conductor inside a magnetic field, the conductor experiences a mechanical force to a direction depending upon the direction of magnetic field and the direction of current in the conductor. The electric current means a flow of charge. In metal it is entirely due to the flow of electrons
in semiconductor, it is due to flow of free electrons as well as holes. In semiconductor, holes move in the direction of conventional current and free electrons move in the opposite of the direction of conventional current. As the electrons have charge, they experience a force while flowing through a conductor placed inside a magnetic field. Due to this force, the electrons get diverted towards one side of the conducted during flowing. As the following charges get shifted to one side of the conductor, there may be a tiny potential difference appeared across the cross-section of the conductor. We call this entire phenomenon as hall effect.
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Torque on a current loop
τ=NIABsinθ
τ=Torque, N=number of loops, I=current A=Area B= magnetic field θ=angle
(a) The equation for torque is derived using this view. Note that the perpendicular to the loop makes an angle θ with the field that is the same as the angle between w/2 and F.
(b) The maximum torque occurs when θ is a right angle and sin θ = 1.
(c) Zero (minimum) torque occurs when θ is zero and sin θ = 0. (d) The torque reverses once the loop rotates past θ = 0.
Motors are the most common application of magnetic force on current-carrying wires. Motors have loops of wire in a magnetic field. When current is passed through the loops, the magnetic field exerts torque on the loops, which rotates a shaft. Electrical energy is converted to mechanical work in the process.
Magnetic Field
A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A charge that is moving in a magnetic field experiences a force perpendicular to its own velocity and to the magnetic field.
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The Biot-Savart Law
The Biot-Savart law states how the value of the magnetic field at a specific point in space from one short segment of current-carrying conductor depends on each factor that influences the field
DC-CIRCUITS
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Kirchhoff's Rules
Kirchhoff First rule/Kirchhoff's current law (1st Law) states that current flowing into a node (or a junction) must be equal to current flowing out of it.
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Kirchhoff's second rule—the loop rule: The algebraic sum of changes in potential around any closed circuit path (loop) must be zero
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Ammeter and Voltmeter
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voltmeter is an instrument used for measuring electric potential difference between two points in an electric circuit. It is connected in parallel
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EMF and terminal voltage
V=E-Ir
where V=terminal voltage , E=electromotive force(E.M.F) ,I=current , r=internal resistance
