問題一覧
1
Alternating current
is an electric current that changes direction at regular intervals.
2
The polarity or direction of an induced current can be reversed
all the above
3
Back emf
is the emf induced in a motor’s coil that tends to reduce the current in the coil of a motor.
4
states that “The magnetic field of the induced current is in a direction to produce a field that opposes the change causing it
Lenz’s Law
5
Alternating current can be converted to direct current by using a device called a ——- to change the direction of the current
commutator
6
Motors are machines that convert mechanical energy to electrical energy
false
7
The purpose of using the Right Hand Rule with the current carrying wire is
to identify the magnetic field direction
8
L
length of current carrying wire (meter m)
9
F(magnetic)
magnetic force (newton n)
10
A …… produces a continuously changing emf.
generator
11
What will happen when you insert an iron rod inside the solenoid
the magnetic field will increase
12
The magnitude of the induced emf be increased by
Increasing the velocity of the wire as it moves through the magnetic field.
13
I
current ( ampere A)
14
When a bar magnet and coil approach each other, the magnetic field produced by the induced current in the coil ——- the approaching magnetic field of the bar magnet.
repels
15
The current be induced in a circuit
when a closed circuit moves through a magnetic field.
16
V
velocity of charge motion( meter per second m/s)
17
q
charge (coulomb c)
18
is an important electrical device which is based on mutual inductance.
transformer
19
A generator is a machine that converts mechanical energy into electrical energy.
true
20
when you insert an iron rod inside the solenoid,
the magnetic field will increase
21
B
magnetic field (Tesla t)
22
Mutual inductance
The ability of one circuit to induce an emf in a nearby circuit in the presence of charging current
23
What is the purpose of using the right hand rule with the current carying wire
identifying the magnetic field direction