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CBSE Questions for Class 10 Physics Magnetic Effects Of Electric Current Quiz 2 - MCQExams.com
CBSE
Class 10 Physics
Magnetic Effects Of Electric Current
Quiz 2
What does an electric generator generate?
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Current
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Magnetism
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Gravity
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Light
Explanation
An electric generator is a device that converts mechanical energy to electrical energy using the principle of electromagnetic induction. Hence, it generates electric current for the supply of electrical power to consumers.
A current is passed through a straight wire. The magnetic field established around it has its lines of forces :
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circular
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parabolic
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elliptical
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no fixed shape
Explanation
The magnetic field lines forms concentric circles around a current carrying wire as shown in the figure.
Alternating current is one which changes in its :
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direction
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magnitude
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magnitude and direction both
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none
Explanation
Answer is C.
An alternating current (AC) is an electric current whose magnitude and direction vary, unlike direct current, whose direction remains constant.
The usual waveform of an AC power circuit is a sine wave, because this leads to the most efficient transmission of energy. The sine wave oscillates periodically between positive and negative direction.
The AC produced in India changes its direction in every :
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$$\displaystyle \frac{1}{100}$$ second
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100 second
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50 second
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None of these
Explanation
Answer is A.
In India, the frequency of AC voltage is $$50\ Hz$$.
It means $$50$$ waves will be produced in $$1\ s$$.
In one wave, the direction is changed $$2$$ times.
Thus, in 50 waves, the direction will be altered $$50\times 2=100$$ times.
i.e. the direction is changed $$100$$ times in $$1\ s$$.
Thus the direction is changed in every $$\dfrac{1}{100}\ s$$.
When a bar magnet is broken into two pieces:
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we will have a single pole on each piece
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each piece will have two unlike poles
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each piece will have two like poles
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none of these
Explanation
When we break a magnet into two, both act as magnets, that is both have a north and south pole each. In both these pieces the corresponding north and south poles remain on the sides as in the original magnet. This means that the 2 broken sides must get oppositely polarized.
Magnetic field is a
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Vector quantity
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Scalar quantity
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Scalar as well as vector quantity
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Neither vector nor scalar
Explanation
Answer is A.
The magnetic field at any point in space is a vector quantity.
This means there is a direction associated with the field as well as a field strength. Consider the arrow below:
The direction of the arrows can be thought of as the direction of the magnetic field. The length of the arrows can be thought of as the strength of the field, i.e. the longer the arrows, the stronger the field.
A D.C. generator is based on the principle of.
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magnetic effect ofcurrent
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lighting effect ofcurrent
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electrochemical induction
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electromagnetic induction
Explanation
The answer is D.
Electromagnetic induction is a process where a conductor placed in a changing magnetic field (or a conductor moving through a stationary magnetic field) causes the production of a voltage across the conductor. This process of electromagnetic induction, in turn, causes an electrical current - it is said to be the induced current.
Hence, the D.C. generator is based on the principle of electromagnetic induction.
The electrode potential of the neutral wire in a mains supply cable is
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5V
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0V
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15V
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220V
Explanation
Answer is B.
The neutral wire is earthed, usually at the local substation, thus
the neutral wire is at earth potential which is nothing but zero potential.
The earth wire is generally black in colour.
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True
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False
Explanation
The earth wire, which has insulation of green color, is usually connected to a metal plate deep in the earth near the house. This is used as a safety measure, especially for those appliances that have a metallic body, for example, electric press, toaster, table fan, refrigerator, etc.
Which of the following is not a type of wire in power supply.
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Phase Wire
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Neutral wire
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Zero wire
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Earth wire
Explanation
In power supply system, there are three wires.
One of the wires in this supply, usually with red insulation cover, is called live wire (or positive). Another wire, with black insulation, is called neutral wire (or negative). The earth wire, which has insulation of green colour, is usually connected to a metal plate deep in the earth near the house.
H
ence there is no such wire named Zero wire.
Answer is Option C.
In our houses all electrical devices operate on 220 V. It implies that
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they are connected in parallel
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they are connected in series
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they all have currents of equal values
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they all have the same resistance
Explanation
Voltage across the appliance connected in parallel is the same.
As the voltage across all the appliances is same and equals to $$220$$ V, this means that all the appliance must be connected in parallel.
A vertical wire carrying current in the downward direction is placed in a horizontal magnetic field directed northwards. The direction of the force on the wire is ________.
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Eastward
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Northward
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Upwards
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Westward
Explanation
According to Fleming's Left-hand rule, stretch your left hand in such a way that; the middle finger in the direction of current flow (Vertically downward), index finger in the direction of magnetic field ( Northwards). The direction of thumb will show the direction of force acting on the conductor that would be in
Eastward direction.
The colour of the earth wire is generally :
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red
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blue
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black
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green
Explanation
The colour of an earth wire is generally green.
How can you determine direction of magnetic field lines around a current carrying conductor
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Left hand Thumb Rule
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Right Hand Thumb Rule
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By rotating the conductor
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Using sonometer
Explanation
Direction of magnetic field lines around a current carrying conductor can be found by Right Hand Thumb Rule.
Imagine that you are holding a current-carrying straight conductor in your right hand such that the thumb points towards the direction of current. Then your fingers will wrap around the conductor in the direction of the field lines of the magnetic field.
A solenoid with a soft iron core is called a _____.
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Electromagnet
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Magnet
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Conducts
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Insulator
Explanation
The combination of a solenoid and a soft iron core operates on the basis of the magnetic effect of electric current i.e,
it shows magnetic behavior on the flow of current, and thus its an electromagnet.
Which of the following uses the principle of electromagnetic induction?
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Electric generator
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Water Cooler
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Solar Cell
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Electrical Battery
Explanation
The change in magnetic field lines associated with a coil is the cause of induced electric current in it.
This is the principle of Electromagnetic induction. This change can be achieved by:
by moving the coil in a magnetic field or
by changing the magnetic field around the coil.
Electr
ic generator uses this principle in which a coil rotates in a magnetic field such that the current is induced in it due to the change in magnetic field lines linked with it.
Which of the following defines electromagnetic induction:
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When the magnetic field associated with a coil changes, an induced electric current flows through the coil.
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Electric current induces magnetic field near the wire carrying current.
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Two permanent magnets exert force on each other.
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Electrolyte disintegrates into ions in a battery.
Explanation
The magnetic field associated with a coil is the magnetic flux flowing normally to the surface area of the current-carrying coil. When it changes, an emf is produced opposing the cause. This is the principle of Electromagnetic induction.
Production of electricity from magnetism is called
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Electric field
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Magnetic field lines
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Electromagnetic induction
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Magnetic induction
Explanation
The production of electricity from magnetism is electromagnetic induction. Electric current can produce magnetism and the reverse is also true.
Potential difference of $$220-250\ V$$ is present between:
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Earth wire and neutral wire
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Live wire and earth wire
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Live wire and neutral wire
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B and C both
Explanation
The potential difference between a live wire and the neutral wire is about $$220\ V-250\ V$$. which is generally provided for household purposes in homes for electricity.
In the statement of Fleming's left hand rule, what do the direction of centre finger represents
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motion
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magnetic field
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current
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none
Explanation
The direction of the current and that of the magnetic field perpendicular to each other and found that the force is perpendicular to both of them. The three directions can be illustrated through a simple rule, called Fleming
s left-hand rule. According to this rule, stretch the thumb, forefinger and middle finger of your left hand such that they are mutually perpendicular. If the first finger points in the direction of magnetic field and the second finger in the direction of the current, then the thumb will point in the direction of motion or the force acting on the conductor.
Magnetic field has
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Magnitude
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Direction
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Both
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None
Explanation
We know that
$$\overset { \rightarrow }{ B } =\dfrac { { \mu }_{ 0 }Il }{ 4\pi { r }^{ 2 } } $$
Thus has magnitude and direction is obtained by different laws as per the direction of current.
Electromagnetic induction is the :
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charging of a body with a positive charge
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production of current by relative motion between a magnet and a coil
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rotation of the coil of an electric motor
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generation of magnetic field due to a current carrying solenoid
Explanation
$$\bullet$$Electromagnetic induction is the
production of current by relative motion between a magnet and a coil.
$$\bullet$$T
he phenomenon of producing electric current in a conductor by moving it perpendicular to a magnetic field or vice -versa, is called electro magnetic induction.
Suggest way/s in an a.c. generator to produce a higher e.m.f.
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By increasing the speed of rotation of coil
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By increasing the number of turns in the coil
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both A & B
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None of the above
Explanation
C. both A & B.
In an a.c. generator to produce a higher emf-
1. By increasing the speed of rotation of the coil.
2. By increasing the number of turns in the coil.
I
n a current carrying conductor, if the direction of magnetic field and that of the current are mutually perpendicular to each other, then the force acting on the conductor will be
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perpendicular to both
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perpendicular to direction of current
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perpendicular to direction of field.
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none
Explanation
A current-carrying conductor, when placed in a magnetic field, experiences a force. If the direction of the field and that of the current are mutually perpendicular to each other, then the force acting on the conductor will be perpendicular to both and will be given by Fleming
s left-hand rule. This is the basis of an electric motor. An electric motor is a device that converts electric energy into mechanical energy.
An electric generator actually acts as :
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Source of electric charge
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Source of heat energy
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An electromagnet
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A converter of energy
Explanation
A
n electric generator is a machine that generates electricity by using the principle of electromagnetic induction. It converts mechanical energy to electrical energy.
An electric motor works on the principle:
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of electromagnetic induction
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when a rectangular coil is placed in a magnetic field and current is passed through it, a force acts on the coil which rotates it continuously.
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both A and B
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None of the above
Explanation
An electric motor utilises the magnetic effect of current. It works on the
principle that when a rectangular coil is placed in a magnetic field and current is passed through it, a force acts on the coil which rotates it continuously.
Mark the incorrect statement.
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electric current produces magnetism.
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magnets can produce electric current.
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magnets can't produce electric current.
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a and b
Explanation
A magnet can generate electric current by the means of electromagnetic induction. When there is a relative motion between a coil and a magnet, the magnetic flux linked to the coil changes due to that relative motion. This change in magnetic flux will induce a current in the coil, which is known as $$induced\ current$$.
All appliances in a domestic electric circuit are connected in parallel so that
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Voltage drop across each appliance is same.
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Current through each appliance is same.
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Power consumed by each appliance is same.
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It allows amplification of power
Explanation
Electrical appliances are connected in a parallel arrangement in a house circuit because each appliance gets full voltage as resistance in a parallel arrangement is low. If one appliance fuses, it does not affect the working of other appliances. We can use one appliance without using other appliances.
A coil of insulated copper wire is connected to a galvanometer. What would happen if a bar magnet is (i) Pushed into the coil?
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The galvanometer shows deflection
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The galvanometer do not show any deflection
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Current increases inside the coil
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none
Explanation
D
ue to change in magnetic flux linked with coil, the galvanometer shows deflection (say towards right). The galvanometer will show a deflection towards left when the bar magnet is withdrawn from inside the coil.
In the statement of Fleming's left hand rule, force acting on the conductor is represented by
Report Question
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thumb
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fore finger
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middle finger
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none
Explanation
The direction of the current and that of the magnetic field perpendicular to each other and found that the force is perpendicular to both of them. The three directions can be illustrated through a simple rule, called Fleming
s left-hand rule. According to this rule, stretch the thumb, forefinger and middle finger of your left hand such that they are mutually perpendicular. If the first finger points in the direction of magnetic field and the second finger in the direction of the current, then the thumb will point in the direction of motion or the force acting on the conductor.
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