Moving charges and magnetism Flashcards
force due to a magnetic field
F=q(VxB)
v–>velocity of charge
B–>magnetic field
! obtained direction for +ve charge(for eg upward) is opposite to
direction for -ve charge(for eg downward)
Lorentz force
1)the force experienced by a charge in an external electric field and magnetic field
2)F = qE(force due to electric field) + qv × B
force on current carring conductor
F=BIL sin(theta)
where theta –>angle between conductor and magnetic field
(use flemings left hand rule[FBI] to determine the direction)
motion of charged particle in a magnetic field(when it is parallel or anti parallel to the magnetic field)
no change because force due to magnetic field is zero
motion of charged particle in a magnetic field(perpendicular)
find its responding formula
1)circular motion with constant velocity and direction keeps changing
2) r=mv/qb
r–> radius of circular path
m–>mass of particle
b–>magnetic field
3)anglular velocity(omega)=qb/m [by v=r omega]
4)f=qb/2pim [by 1/T where T=2*pi/omega]
motion of charged particle in a magnetic field(the particle is projected with an angle theta)
it follows a helical path(spring)
relationship between epsilon and mu
epsilon * mu = 1/c^2
magnetic field due to a finite current carring conductor
B=(μ/4*pi) * I/d(sin x+sin y)
where
d–> distance between the point and conductor
i–> current
x–>angle between the top and middle of the conductor
y–>angle between the conductor’s middle and bottom
Magnetic field on the axis of a circular current loop
(μIR^2) / 2*[R^2+X^2]^(3/2)
where
R–>radius of sphere
x–>distance from center of the circle to the point
magnetic field due to a infinity long straight conductor
B= μi/2pir
ampere circuital law
the line integral of the magnetic field surrounding closed-loop equals to the number of times the algebraic sum of currents passing through the loop
∮B dl = μ i(enclosed)
force per unit length due to parallel current
F12=μi1i2/2pid
torque on a rectangular current loop in a uniform magnetic field
tau(T)= B * I * A(area of rectangular loop)
torque on a rectangular current loop in a uniform magnetic field at angle theta
tau(T)= iabsin(theta)
where ia=
current in a moving coil galvanometer
I = (C/nBA) × θ
I–>The current in the moving coil galvanometer
C–>The torsional constant of the spring
resistance of ideal ammeter
0
current sensitivity
NAB/K
voltage sensitivity
NAB/(K*R)
what is the effect of current density on voltage sensitivity
1)no effect
2)if current density is doubled voltage sensitivity need not to be
increased
magnetic field at centre of circular current loop
B=μ I/2r
