4263914
Questão 1
Questão
Soft magnetic materials are hard to magnetise but stay magnets for longer periods
Responda
- True
- False
Questão 2
Questão
With a steady current in an electromagnet no e.m.f is needed because the magnetic field is not changing
Responda
- True
- False
Questão 3
Questão
To make an electromagnet stronger one can...
Responda
-
put more coils on the wire
-
run more electrical current through the wire
-
use an iron core
-
use a permanent magnet
Questão 4
Questão
When a magnet moves into a coil of wire, a voltage is induced and current flows...
What kind of current is this?
Responda
-
Direct Current (DC)
-
Alternating Current (AC)
Questão 5
Questão
What is electromagnetic induction?
Responda
-
When a magnet cuts through a conductor resulting in a flow of current
-
To start an alternating current of electricity using an electromagnet
-
Creating an electromagnet out of a metal
Questão 6
Questão
If there are more coils on the primary coil than on the secondary coil it is [blank_start]a step down[blank_end]
Responda
-
a step down
-
a step up
-
a transformer
Questão 7
Questão
A.C p.d is produced in the...
Responda
-
secondary coil
-
primary coil
Questão 8
Questão
The A.C in the [blank_start]primary coil[blank_end] produces [blank_start]an alternating[blank_end] magnetic field
Responda
-
primary coil
-
secondary coil
-
an alternating
-
a direct
Questão 9
Questão
([blank_start]p.d[blank_end] across [blank_start]primary coil[blank_end] (v) / ([blank_start]p.d[blank_end] across [blank_start]secondary coil[blank_end] (v)) = ([blank_start]number of turns[blank_end] on [blank_start]primary coil[blank_end] / [blank_start]number of turns[blank_end] on [blank_start]secondary coil[blank_end])
Responda
-
p.d
-
Amps
-
primary coil
-
secondary coil
-
p.d
-
Amps
-
secondary coil
-
primary coil
-
number of turns
-
e.m.f
-
primary coil
-
secondary coil
-
number of turns
-
e.m.f
-
secondary coil
-
primary coil
Questão 10
Questão
A long coil with many turns is called a [blank_start]solenoid[blank_end]
Responda
-
solenoid
Questão 11
Questão
Relays are used to break a circuit if the electrical current is too high
Responda
- True
- False
Questão 12
Questão
Why is iron a better core to use for an electromagnet?
Responda
-
steel is a hard metal and would become permanently magnetised
-
steel is a soft metal and would lose its magnetic ability to quickly
-
steel is not magnetic
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