Question

A flat coil of radius 4 cm has 30 turns and a resistance of
0.15 Ω, and is placed on a horizontal table.

Initially, a uniform magnetic field of 0.75 T pointing upward
(viewed from an observer above the table) passes through the coil.
In 0.25 s, the magnitude of the magnetic field is changed to 0.35 T
and the direction is completely reversed.

(a) Determine the direction of the induced current in the
coil. 2%

Answer: ______________

Explain in detail:

(b) Find the average induced current in the loop. 3%

Answer: ___________

Answer #1

(a)

direction of the induced current in the coil = counterclockwise (from lenz's law)

according to lenz law, induced current oppose the changing flux.

point your thumb in upward decreasing field and curl your firgers.

Here the direction of curling is counterclockwise. so, the direction of current is CCW.

(b)

lnduced emf in the loop,

e = -N*d / dt

e = -N*(B*A*cos) / dt

e = -30*[(0.35 - (-0.75))*pi*0.04^2*cos180] / 0.25

e = 0.6635 V

average induced current in the loop,

i = e / R

i = 0.6635 / 0.15

i = 4.42 A

A flat circular coil with 96 turns, a radius of 3.72 10-2 m, and
a resistance of 0.432 Ω is exposed to an external magnetic field
that is directed perpendicular to the plane of the coil. The
magnitude of the external magnetic field is changing at a rate of
ΔB/Δt = 0.837 T/s, thereby inducing a current in the coil. Find the
magnitude of the magnetic field at the center of the coil that is
produced by the induced current.

2. A circular coil with 30 turns of wire has a diameter of 2.00
cm. The total resistance of the coil is 0.350 Ω. An applied uniform
magnetic field is directed upward, perpendicular to the plane of
the coil.
a) If the magnetic field changes linearly from 0.000 T to 0.800
T in 0.500 s, what is the induced emf in the coil while the field
is changing?
b) What is the magnitude and direction (CW or CCW when looked...

A circular coil of radius 4.0 cm, resistance 0.30 Ω, and 100
turns is placed in a uniform magnetic field at an angle of 30° with
the plane of the coil. The magnitude of the field changes with time
according to ?(?)=20?^(−0.3?) (in Tesla, t is time in seconds).
What is the value of the current induced in the coil at the time t
= 2.0 s?

A circular coil of wire with 5 turns and a radius of 4.0 cm lies
flat on a table in a region where the magnetic field is 4.5 mT up.
The coil is flipped over in a time of 0.25 s. Is an emf induced in
the coil? If so, what is its average value?

A flat circular coil having 15 turns, each of a radius of 18.0
cm, is in a uniform and steady 0.130-T magnetic field. The coil has
a resistance of 8.00
a) Find the total magnetic flux through one turn of the coil
when the field is parallel to the axis of the coil.
b) If the coil is rotated in 12.0 ms so its axis is
perpendicular to the field, find the average induced voltage and
the induced current in...

A 5.0-cm-diameter coil has 20 turns and a resistance
of 0.50 Ω. A magnetic field "parallel" to the coil's axis is B =
0.020t + 0.010t2, where B is in tesla and t is in seconds.
a) Find an expression for the induced current I(t) as
a function of time.
b) Evaluate I at t = 10 s and t = 20 s.

A flat, circular coil has 40 turns of radius 3.6 cm. At t=0 an
external magnetic field perpendicular to the plane of the coil has
a value of 0.32 T and is decreasing linearly with time. At t = 0,
the induced emf is 65 mV. How long does it take for the field to
reach zero?

A circular wire loop 39 cm in diameter has resistance 120 Ω and
lies in a horizontal plane. A uniform magnetic field points
vertically downward, and in 25 ms it increases linearly from 5.0 mT
to 55 mT.
Find the magnetic flux through the loop at the beginning. (
Φ1 =
? mWb
)
Find the magnetic flux through the loop at the end of the 25-ms
period. Φ2 = ? mWb
What's the loop current during this time?
Express...

A circular coil of 312 winds of wire (radius = 7.0 cm,
resistance = 7.4 Ω) is placed in a uniform magnetic field that is
perpendicular to the plane of the loop. The magnitude of the field
changes with time according to ? = 90sin(7?) mT, where ? is
measured in seconds. Determine the magnitude of the current induced
in the loop at ?=?/7 s.

A circular loop of radius 14 cm carries a current of 15 A. A
flat coil of radius 1.2 cm, having 65 turns and a current of 1.1 A,
is concentric with the loop. The plane of the loop is perpendicular
to the plane of the coil. Assume the loop's magnetic field is
uniform across the coil. What is the magnitude of (a) the magnetic
field produced by the loop at its center and (b) the torque on the
coil...

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