Module 1 Flashcards
independently
discovered that magnetism could
produce an electric current in a wire
Michael Faraday and Joseph Henry
an electric current can be induced in a circuit by
a changing magnetic field
an induced emf is produced in the secondary circuit by the
changing magnetic field
The emf (electromotive force) induced in a circuit is ____ to the
time rate of change of the magnetic flux through the circuit.
directly proportional
emf
electromotive force
Ways of Inducing an emf
- Magnetic field can change over time.
- Area enclosed by the loop can change over time.
- Angle between magnetic field and loop’s normal can change over time.
the production of an electromotive force (i.e., voltage) across an electrical conductor due to its dynamic interaction with a magnetic field.
Electromagnetic Induction
APPLICATION OF ELECTROMAGNETIC INDUCTION:
- electric generator
- eddy currents
- transformers
When a magnet is moved toward the loop, the galvanometer needle
deflects in one
direction
When the magnet is moved away from the loop, the needle
deflects in the opposite direction
When the magnet is held stationary relative to the loop
no deflection is observed
if the magnet is held stationary and the loop is moved either toward or away from it
the needle deflects
What is electromagnetic induction
A. The production of an electric current created by a varying magnetic field
B. The production of the magnetic field, accomplished by running a
current through a coil of wire
C. Creating electromagnetic fields by any purposeful means
D. Building a magnet
A
If a wire is moved perpendicular to the magnetic field, what is induced
across the ends of the wire
A. area
B. coil
C. magnetic field
D. potential difference
D
All matters are said to be neutral wherein the numbers of electron and protons are
equal so once charges it do not stay for a long time because of the following factors
except;
A. faster
B. slower
C. in opposite direction
D. parallel to the magnetic field
A
the amount of induced potential difference can be increased if the wire is
moved in the magnetic field ___________
A. generating electricity
B. energy efficient cookers and burners
C. energy-efficient motors
D. using a magnet to separate scrap metal parts
D
Which of the following is NOT a way that a magnetic field can be varied to
induce a current in a wire?
A. Move the coil in and out of the magnetic field
B. Rotate the coil inside the magnetic field
C. Move the coil once it is already fully inside the magnetic field
D. Change the strength of the magnetic field
B
A voltage will be induced in a wire loop when the magnetic field within
that loop
A. changes
B. aligns with the electric field
C. is at the right angle to the electric field
D. converts to magnetic energy
A
If you change the magnetic field in a closed loop of wire, you induce
in the loop a
A. current
B. voltage
C. electric field
D. all of the above
D
Which of the following equations correctly describes Faraday’s law of
induction?
emf = -N ((ABcosθ)/t)
The essential concept in an electric motor and a generator is
A. Coulomb’s law
B. Ohm’s law
C. Faraday’s law
D. Newton’s second law
C
Which of the following would not increase the emf produced by a
generator?
A. rotating the generator coil faster
B. increasing the strength of the generator magnets
C. increasing the number of turns of wire in the coil
D. reducing the cross-sectional area of the coil
D
