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Which of the following correctly describes the magnetic field near a long straight wire?
(a) The field consists of straight line perpendicular to the wire.
(b) The field consists of straight lines parallel to the wire.
(c) The field consists of radial lines originating from the wire.
(d) The field consists of concentric circles centred on the wire.
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The phenomena of electromagnetic induction is
(a) the process of charging a body
(b) the process of generating magnetic field due to a current passing through a coil
(c) producing induced current in a coil due to relative motion between a magnet and the coil
(d) the process of rotating a coil of an electric motor
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The device used for producing electric current is called a:
(a) generator (b) galvanometer
(c) ammeter (d) motor
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The essential difference between AC generator and a DC generator is that
(a) AC generator has an electromagnet while a DC generator has permanent magnet,
(b) DC generator will generate a higher voltage,
(c) AC generator will generate a higher voltage,
(d) AC generator has slip rings while the DC generator has a commutator.
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At the time of short-circuit, the current in the circuit
(a) reduces substantially (b) does not change
(c) increases heavily (d) varies continuously
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State whether the following statements are true or false.
(a) An electric motor converts mechanical energy into electrical energy.
(b) An electric generator works on the principle of electromagnetic induction.
(c) The field at the centre of a long circular coil carrying current will be parallel straight lines.
(d) A wire with a green insulation is usually the live wire.
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List three sources of magnetic fields.
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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.
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When is the force experienced by current-carrying conductor placed in a magnetic field is largest?
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Imagine that you are sitting in a chamber with your back to one wall. An electron beam, moving horizontally from back wall towards the front wall, is deflected by a strong magnetic field to your right side. What is the direction of the magnetic field?
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Draw a labelled diagram of an electric motor. Explain its principle and working. What is the function of a split-ring in an electric motor?
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Name some devices in which electric motors are used.
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A coil of insulated copper wire is connected to a galvanometer. What would happen if a bar magnet is
(i) pushed into the coil?
(ii) withdrawn from inside the coil?
(iii) held stationary inside the coil?
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Two circular coils A and B are placed close to each other. If the current in the coil A is changed, will some current be induced in the coil B? Given reason.
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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.
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Explain the underlying principle and working of an electric generator by drawing a labelled diagram. What is the function of brushes?
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When does an electric short-circuit occur?
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What is the function of an earth wire? Why is it necessary to earth metallic appliances?
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Why does a compass needle get deflected when brought near a bar magnet?
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Draw magnetic field lines around a bar magnet.
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List the properties of magnetic lines of force.
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Why don't two magnetic lines of force intersect each other?
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Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop.
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The magnetic field in a given region is uniform. Draw a diagram to represent it.
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Choose the correct option.
The magnetic field inside a long straight solenoid carrying current
(a) is zero.
(b) decreases as we move towards its end.
(c) increases as we move towards its end.
(d) is the same at all points.
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Which of the following property of a proton can change while it moves freely in a magnetic field? (There may be more than one correct answer.)
(a) mass (b) speed (c) velocity (d) momentum
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In an activity demonstrating the force acting on a current carrying conductor placed in a magnetic field as shown in figure how do we think the displacement of rod AB will be affected if
(a) current in rod AB is increased?
(b) a stronger horse-shoe magnet is used?
(c) length of the rod AB is increased?
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A positively-charged particle (alpha-particle) projected towards west is deflected towards north by a magnetic field. The direction of magnetic field is
(a) towards south (b) towards east
(c) downward (d) upward
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State Fleming's left-hand rule.
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What is the principle of an electric motor?
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What is the role of the split ring in an electric motor?
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Explain different ways to induce current in a coil.
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State the principle of an electric generator.
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Name some source of direct current.
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Which sources produce alternating current?
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Choose the correct option.
A rectangular coil of copper wires is rotated in a magnetic field. The direction of the induced current changes once in each
(a) two revolutions (b) one revolution
(c) half revolution (d) one fourth revolution
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Name two safety measures commonly used in electric circuits and appliances.
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An electric oven of 2 kW power rating is operated in a domestic electric circuit 220 V that has a current rating of 5 A. What result do you expect? Explain.
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What precaution should be taken to avoid the overloading of domestic electric circuits?
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question_answer40)
Choose the incorrect statement from the following regarding magnetic lines
of field
(a) The direction of magnetic field at a point is taken to
be the direction in which the North Pole of a magnetic compass needle points
(b) Magnetic field lines are closed curves
(c) If magnetic field lines are parallel and equidistant,
they represent zero field strength
(d) Relative strength of magnetic field is shown by the
degree of closeness of the field lines
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question_answer41)
If the key in the arrangement as shown below is taken out
(the circuit is made open) and magnetic field lines are drawn over the
horizontal plane ABCD, the lines are
(a) Concentric circles
(b) Elliptical in shape
(c) Straight lines parallel to each other
(d) Concentric circles near the point O but of elliptical
shapes as we go away from it
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question_answer42)
A circular loop placed in a plane
perpendicular to the plane of paper carries a current when the key is ON. The
current as seen from points A and B (in the plane of paper and on the axis of
the coil) is anti-clockwise and clockwise respectively. The magnetic field
lines point from B to A. The N-pole of the resultant magnet is on the face
close to
(a) A
(b) B
(c) A if the current is small and B if the current is
large
(d) B if the current is small and A if the current is
large
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question_answer43)
For a current in a long straight solenoid N and S-poles
are created at the two ends. Among the following statements, the incorrect
statement is
(a) The field lines inside the solenoid are in the form of
straight lines, which indicates that the magnetic field is the same at all
points inside the solenoid
(b) The strong magnetic field produced inside the solenoid
can be used to magnetize a piece of magnetic material like soft iron, when
placed inside the coil
(c) The pattern of the magnetic field associated with the
solenoid is different from the pattern of the magnetic field around a bar
magnet
(c) The N and S-poles exchange position when the direction
of current through thesolenoid is reversed
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question_answer44)
A uniform magnetic field exists in the plane of paper
pointing from left to right as shown in figure. In the field an electron and a
proton move as shown. The electron and the proton experience Proton
(a) Forces both pointing into the plane of paper
(b) Forces both pointing out of the plane of paper
(c) Forces pointing into the plane of paper and out of the
plane of paper, respectively
(d) Force pointing opposite and along the direction of the
uniform magnetic field respectively
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question_answer45)
Commercial electric motors do not use
(a) An electromagnet to rotate the armature
(b) Effectively large number of turns of conducting wire
in the current carrying coil
(c) A permanent magnet to rotate the armature
(d) A soft iron core on which the coil is wound
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question_answer46)
In the arrangement shown in figure, there are two coils
wound on anon-conducting cylindrical rod. Initially, the key is not inserted.
Then the key is inserted and later removed. Then
(a)The deflection in the galvanometer remains zero
throughout
(b) There is a momentary deflection in the galvanometer
but it dies out shortly and there is no effect when the key is removed.
(c) There are momentary galvanometer deflections that die
out shortly, the deflections are in the same direction.
(d) There are momentary galvanometer deflections that die
out shortly, the deflections are in opposite directions. Thus the galvanometer
shows momentary deflections in opposite directions.
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question_answer47)
Choose the incorrect statement.
(a) Fleming's right hand rule is a simple rule to know the
direction of induced current.
(b) The right hand thumb rule is used to find the
direction of magnetic fields due to current carrying conductors.
(c) The difference between the direct and alternating
currents is that the direct current always flows in one direction, where as the
alternating current reverses its direction periodically.
(d) In India, the AC changes direction after every 
second.
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question_answer48)
A constant current flows in a horizontal wire in the plane
of the paper from east to west as shown in figure. The direction of magnetic
field at appoint will be north to south.
(a) Directly above the wire
(b) Directly below the wire
(c) At a point located in the plane of the paper on the
north side of the wire
(d) At a point located in the plane of the paper on the
south side of the wire
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question_answer49)
The strength of magnetic field inside a Long current carrying straight solenoid
is
(a) more at the ends than at the centre (b)
minimum in the middle
(c) same at all points (d)
found to increase from one end to the other
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question_answer50)
To convert an AC generator into DC generator
(a) split ring type commutator must be used (b) slip
rings and brushes must be useda
(c) a stronger magnetic field has to be used a (d)a rectangular
wire loop has to be used
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question_answer51)
The most important safety method used for protecting home
appliances from short circuiting or overloading is
(a) earthing (b) use of fuse (c)
use of stabilizers (d) use of electric meter
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question_answer52)
A magnetic compass needle is placed in the plane of paper near point A as
shown in figure .In which plane should astraight current carrying conductor be
placed so that it passes through A and there is no change in the deflection of
the compass? Under what condition is the deflection maximum and why?
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question_answer53)
Under what conditions permanent electromagnet is obtained
if a current carrying solenoid is used? Support your answer with the help of a labelled
circuit diagram.
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question_answer54)
AB is a current carrying conductor in the plane of the
paper as shown in figure. What are the directions of magnetic fields produced
by it at points P and Q? Given 
,
where will the strength of the magnetic field be larger?
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question_answer55)
A magnetic compass shows a deflection, when placed near a
current carrying wire. How will the deflection of the compass get affected, if
the current in the wire is increased? Support your answer with a reason.
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question_answer56)
It is established that an electric current through a
metallic conductor produces a magnetic field around it. Is there a similar
magnetic field produced around a thin beam of moving (i) alpha particles, (ii)
neutrons?
Justify your answer.
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question_answer57)
What does the direction of thumb indicate in the right-hand
thumb rule?
In what way this rule is different from Fleming's
Left-hand rule.
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question_answer58)
Meena draws magnetic field lines of field close to the
axis of a current carrying circular loop. As she moves away from the centre of
the circular loop she observes that the lines keep on diverging. How will you
explain her observation?
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question_answer59)
What does the divergence of magnetic field lines near the
ends of acurrent carrying straight solenoid indicate?
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question_answer60)
Name four appliances wherein an electric motor, a rotating device that converts
electrical energy to mechanical energy, is used as an important component. In
what respect motors are different from generators?
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question_answer61)
What is the role of the two conducting stationary brushes
in a simple electric motor?
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question_answer62)
What is the difference between a direct current and an alternating current?
How many times does AC used in India change direction in one second?
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question_answer63)
What is the role of fuse, used in series with any
electrical appliance ?Why should a fuse with defined rating not be replaced by
one with a larger rating?
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question_answer64)
Why does a magnetic compass needle pointing north and south in the absence
of a nearby magnet get deflected when a bar magnet or a current carrying loop
is brought near it? Describe some salient features of magnetic lines of field
concept.
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question_answer65)
With the help of a labelled circuit diagram illustrate the pattern of
field lines of the magnetic field around a current-carrying straight long conducting
wire. How is the right hand thumb rule useful to direction of magnetic field
associated with a current-carrying conductor?
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question_answer66)
Explain with the help of a labelled diagram the distribution
of magnetic field due to a current through a circular loop. Why is it that if a
current carrying coil has n turns the field produced at any point is n times as
large as that produced by a single turn?
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question_answer67)
Describe the activity that shows that a current-carrying
conductor experiences a force perpendicular to its length and the external magnetic
filed. How does Fleming's left-hand rule help us to find the direction of the
force acting on the current-carrying conductor?
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question_answer68)
Draw a labelled circuit diagram of a simple electric motor
and explain its working. In what way these simple electric motors are different
from commercial motors?
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question_answer69)
Explain the phenomenon of electromagnetic induction.
Describe an experiment to show that a current is set up in a closed loop when
an external magnetic field passing through the loop increases or decreases.
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question_answer70)
Describe the working of an AC generator with the help of a
labelled circuit diagram. What changes must be made in the arrangement to convert
into a DC generator?
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question_answer71)
Draw an appropriate schematic diagram showing common domestic circuits
and discuss the importance of fuse. Why is it that a burnt out fuse should be
replaced by another fuse of identical rating?
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