Moving charges and magnetism

Question 1

force due to a magnetic field

Answer 1

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)

Question 2

Lorentz force

Answer 2

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

Question 3

force on current carring conductor

Answer 3

F=BIL sin(theta)
where theta –>angle between conductor and magnetic field
(use flemings left hand rule[FBI] to determine the direction)

Question 4

motion of charged particle in a magnetic field(when it is parallel or anti parallel to the magnetic field)

Answer 4

no change because force due to magnetic field is zero

Question 5

motion of charged particle in a magnetic field(perpendicular)
find its responding formula

Answer 5

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]

Question 6

motion of charged particle in a magnetic field(the particle is projected with an angle theta)

Answer 6

it follows a helical path(spring)

Question 7

relationship between epsilon and mu

Answer 7

epsilon * mu = 1/c^2

Question 8

magnetic field due to a finite current carring conductor

Answer 8

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

Question 9

Magnetic field on the axis of a circular current loop

Answer 9

(μIR^2) / 2*[R^2+X^2]^(3/2)
where
R–>radius of sphere
x–>distance from center of the circle to the point

Question 10

magnetic field due to a infinity long straight conductor

Answer 10

B= μi/2pir

Question 11

ampere circuital law

Answer 11

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)

Question 12

force per unit length due to parallel current

Answer 12

F12=μi1i2/2pid

Question 13

torque on a rectangular current loop in a uniform magnetic field

Answer 13

tau(T)= B * I * A(area of rectangular loop)

Question 14

torque on a rectangular current loop in a uniform magnetic field at angle theta

Answer 14

tau(T)= iabsin(theta)
where ia=

Question 15

current in a moving coil galvanometer

Answer 15

I = (C/nBA) × θ
I–>The current in the moving coil galvanometer
C–>The torsional constant of the spring

Question 16

resistance of ideal ammeter

Answer 16

0

Question 17

current sensitivity

Answer 17

NAB/K

Question 18

voltage sensitivity

Answer 18

NAB/(K*R)

Question 19

what is the effect of current density on voltage sensitivity

Answer 19

1)no effect
2)if current density is doubled voltage sensitivity need not to be
increased

Question 20

magnetic field at centre of circular current loop

Answer 20

B=μ I/2r