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Title: MY NOTES
Description: it deals with all the required topics on a particular subject.for eg; maths:triangles ,proof of pythagoras theorem....... etc.
Description: it deals with all the required topics on a particular subject.for eg; maths:triangles ,proof of pythagoras theorem....... etc.
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SCIENCE
Class – 10
Chapter - 13
Magnetic Effects of Electric Current
1
...
(b) The field consists of straight lines parallel
to the wire
...
(d) The field consists of concentric circles
centred on the wire
...
Explanation: The magnetic field lines around a
straight current-carrying conductor are concentric
circles and the centres of these circles lie on the
wire
...
The phenomenon of electromagnetic induction
is
(a) the process of charging a body
...
(c) producing induced current in a coil due to
relative motion between a magnet and the
coil
...
Answer: The correct option is (c)
...
This phenomenon is called electromagnetic
induction
...
The device producing electric is called a
(a) generator
...
(c) ammeter
...
Answer: The correct option is (a)
...
An electric generator converts
mechanical energy into electric energy
...
The essential difference between an AC
generator and DC generator is that
(a) AC generator has an electromagnet while
DC generator has permanent magnet
...
(c) AC generator will generate a higher
voltage
...
Answer: The correct option is (d)
...
5
...
(b) does not change
...
(d) vary continuously
...
Explanation: In the case of short-circuit, the
resistance of the circuit becomes zero
...
6
...
(a) An electric motor converts mechanical
energy into electrical energy
...
(c) The field at the centre of a long circular coil
carrying current will be parallel straight
line
...
Answer:
(a) False
Explanation: An electric motor converts electrical
energy into mechanical energy
...
It works on the principle of
electromagnetic induction
...
The magnetic field lines inside the solenoid
are parallel to each other
...
7
...
Answer: Three sources of magnetic fields are as
follows:
(a) A circular current carrying loop
(b) A solenoid
(c) A straight current carrying conductor
...
How does a solenoid behave like a magnet? Can
you determine the north and south poles of a
current-carrying solenoid with the help of a bar
magnet? Explain
...
When electric current is
passed through it, the magnetic field lines are
produced around it
...
When the north pole of a bar magnet is brought near
the end connected to the negative terminal of the
battery, the solenoid repels the bar magnet
...
Therefore, one end of the solenoid
behaves as a north pole and the other end behaves
as a south pole
...
When is the force experienced by a currentcarrying conductor placed in magnetic field
largest?
Answer: When the direction of electric current is
perpendicular to the direction of the magnetic field,
the force experienced by a current-currying
conductor is maximum
...
Imagine that you are sitting in a chamber with
your back to one wall
...
What is the direction of
magnetic field?
Answer: The direction of magnetic field can be
found with the help of Fleming’s left hand rule
...
As the negatively charged electrons are
moving from back wall to the front wall hence, the
direction of current would be from the front wall to
the back wall
...
Therefore, according to Fleming’s left
hand rule, the direction of magnetic field inside the
chamber would be downward
...
Draw a labelled diagram of an electric motor
...
What is the
function of a split ring in an electric motor?
Answer: An electric motor is a device which converts
electrical energy into mechanical energy
...
When a current is allowed to flow through the coil
ABCD by closing the key, the coil starts rotating anticlockwise
...
Thus, the coil rotates anticlockwise
...
Hence, according to Fleming’s left hand
rule, a downward force acts on the length AB
...
Therefore, an upward force
acts on the length CD
...
After half a rotation, the
position of AB and CD interchanges
...
Hence, the direction of
current in the coil ABCD gets reversed
...
The
reversal of current through the coil ABCD repeats
after each half rotation
...
The split rings help to reverse the
direction of current in the circuit
...
12
...
13
...
What will happen if a bar
magnet is (i) pushed into the coil (ii)
withdrawn from inside the coil and (iii) held
stationary inside the coil?
Answer: A current is induced in a solenoid when a
bar magnet is moved relative to it
...
(i) When a bar magnet is pushed into a coil, a current is
induced for a moment
...
(ii) When the bar magnet is moved away from the coil, a
current is again induced for a moment in opposite
direction
...
(iii) When a bar magnet remains stationary inside the
coil, no current will be induced in the coil
...
14
...
If the current in the coil A is
changed, will some current be induced in the
coil B? Give reason
...
Due to this, an electric current induces
in coil B
...
15: State the rule to determine the direction of a (i)
magnetic field produced around a straight
conductor-carrying current, (ii) force
experienced by a current-carrying straight
conductor placed in a magnetic field which is
perpendicular to it, and (iii) current induced in
a coil due to its rotation in a magnetic field
...
What is the function of brushes?
Answer: It is an electrical device which converts
mechanical energy into electrical energy
...
An electric
generator produces electricity by rotating a coil in a
magnetic field
...
The coil’s axis of rotation
is placed perpendicular to the magnetic field (N-S)
...
The split rings
are then connected to two conducting carbon
brushes X and Y
...
If the coil ABCD is rotated clockwise, then the length
AB moves upwards while length CD moves
downwards
...
Length AB
is moving upwards and the magnetic field acts from
left to right
...
Similarly, the direction of induced
current in the length CD will be from C to D
...
Thus, the
galvanometer shows a deflection in a particular
direction
...
The direction of the induced current in the
coil gets reversed as DCBA
...
In the case of DC generator, instead of slip rings,
two split rings are used
...
The split rings P and Q act as a commutator
...
Hence, a unidirectional current is
produced in a DC generator
...
When does an electric short circuit occur?
Answer: When the resistance of an electric circuit
becomes very low, the magnitude of electric current
flowing through the circuit becomes very high
...
Moreover, when a live wire touches neutral wire
directly, the current flowing in the circuit increases
suddenly
...
18
...
This
avoids any electric shock to the user
...
Title: MY NOTES
Description: it deals with all the required topics on a particular subject.for eg; maths:triangles ,proof of pythagoras theorem....... etc.
Description: it deals with all the required topics on a particular subject.for eg; maths:triangles ,proof of pythagoras theorem....... etc.