I'll have to TRY to answer the others later. I am a Secondary
Four student (Triple-Science, Elect Geog) too, so pardon me if i
make any mistakes.
- AC Generator. The purpose of the slip rings as it
states in the textbook is so that "the alterating induced current
in the coil is transferred to the external circuit". So does that
mean that without the slip rings, the induced e.m.f is lost
to the surroundings or does it keep 'flowing' throughout the coil?
And according to a longman assessment, they stated that the purpose
of the slip rings is so as to prevent the coil from entanglement.
So what exactly is the correct explanation?
Slip rings ensure that the direction of the induced
e.m.f./current flowing in the EXTERNAL circuit changes every half
revolution (that is, every 180 degrees turn) to produce an
ALTERNATING CURRENT (main purpose of A.C. GENERATOR)
The purpose of the slip rings as it states in the
textbook is so that "the alterating induced current in the coil is
transferred to the external circuit". So does that mean that
without the slip rings, the induced e.m.f is lost to the
surroundings or does it keep 'flowing' throughout the
coil? I don't know about this. This is very vague and
debatable (induced current flows in the cables).
The Longman Book is not wrong to say prevention of coil
entanglement, because without the slip rings, try to visualise if
you were to turn the coil. How would the connecting cables in the
EXTERNAL circuit be affected? Or rather, how would the external
circuit, on a whole, be affected?
- Charges. For example, if a positively charged
conductor is allowed to come near the left of an neutral object,
the electrons in the object will be attracted to the left and the
protrons will be repelled away to the right side. Thus, there will
be attraction between the conductor and the object but once they
touch instantaneously, some of the electrons were transferred to
the positive conductor thus causing the object to become positively
charged (since it lost some electrons) and repel away from the
positive conductor, right? Then why is it for example in
crop-spraying it states that the positively charged droplets
induces negative charges on the plants as they come closer to the
plants, allowing attraction. So, when do I know it's induction or
something? And when the droplets reach the plants, does that mean
that the plants become negatively charged or positively
charged?
the electrons in the object will be attracted to the
left and the protrons will be repelled away to the right
side. The protons don't move. It is very easy for them to
find fault with you if you say that the protons are repelled to the
right (although it is not wrong to say so). Just state that
electrons are attracted to the left and the protons are LEFT at the
right, INDUCING the right side with a positive charge (and
vice-versa).
to become positively charged. To be INDUCED
with a positive charge (though I can't find any difference, but my
teacher emphasised on using this)
Then why is it for example in crop-spraying it states
that the positively charged droplets induces negative charges on
the plants as they come closer to the plants, allowing attraction.
So, when do I know it's induction or something? And when the
droplets reach the plants, does that mean that the plants become
negatively charged or positively charged? What textbook
does your school use? Mind uses the Pearson Longman Physics
Insights, 2nd Edition (no sorry, I don't have a scanner). Mine
gives an example on Electrostatic Paint Spraying. I think you just
have to understand that induction precedes attraction. Induce
negative charges on plant --> attraction --> charges between
droplets and plant are neutralised (since they come into contact)
--> electrically neutral plant.
Very very well done. You are well on your way to an A1 :D
I shall add on a bit
The purpose of the slip rings as it states in the
textbook is so that "the alterating induced current in the coil is
transferred to the external circuit". So does that mean that
without the slip rings, the induced e.m.f is lost to the
surroundings or does it keep 'flowing' throughout the
coil? I don't know about this. This is very vague and
debatable (induced current flows in the cables).
Without slip rings, or rather, without a complete circuit, there
will be no induced current. Rather, there will be an induced
voltage.
The reason is because of the force on the moving electrons. When
wires move in a magnetic view, you can visualise lots of electrons
moving in the wire moving in the field as well... Something like
that... There will be a force on the electrons to move to one side,
and hence creating a potential difference. If it is a complete
circuit, these electrons will continue to move in the circuit,
resulting in the induced current :D
