CBSE Class 10 Science Magnetic Effects of Electric Current MCQs

Question. A tesla is equivalent to a
(a) newton per coulomb
(b) newton per ampere-meter
(c) ampere per newton
(d) newton per ampere-second
Answer : B

Question. Which of the following correctly describes the magnetic field near a long straight wire?
(a) The field consists of straight lines 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.
Answer : D

Question. Magnetic field due to a current through a straight conductor depends on
(a) current
(b) distance from the wire
(c) Both (a) and (b)
(d) cross-sectional area of wire
Answer : C

Question. The effective length of the magnet is
(a) the complete length of the magnet
(b) the distance between the two poles of the magnet
(c) the half of the length of the magnet
(d) the square of the length of the magnet
Answer : B

Question. The magnetic field at a distance r from a long wire carrying current I is 0.4. Tesla. The value of magnetic field at a distance 2r is
(a) 0.2 T
(b) 0.1 T
(c) 0.15 T
(d) 1 T
Answer : A

Question. A vertical wire carries a current upward. The magnetic field north of the wire will be directed
(a) upward
(b) eastward
(c) westward
(d) northward
Answer : C

Question. 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
Answer : D

Question. By removing the inducing magnet, the induced magnetism is
(a) Finished after some time
(b) Finished just after
(c) Not finished for a long time
(d) Not changed
Answer : B

Question. Which of the following processes will not produce new magnetic poles?
(a) cutting a bar magnet in half
(b) turning on a current in a solenoid
(c) running a current through a straight wire
(d) placing an iron rod in contact with a magnet
Answer : C

Question. Which of the following is not true
(a) Induction precedes attraction
(b) We cannot isolate a single pole
(c) We can magnetise an iron ring
(d) A permanent magnet retains its magnetism even when heated on a flame.
Answer : D

Question. A ship is to reach a place 8c south of west. In what direction should the ship be steered if declination at the place is 18c west?
(a) West of magnetic south at angle 64c
(b) East of magnetic north at angle 64c
(c) West of magnetic south at angle 50c
(d) East of magnetic north at angle 18c
Answer : A

Question. Which of the following statement is not correct about two parallel conductors carrying equal currents in the same direction?
(a) Each of the conductors will repel each other.
(b) The two conductors will repel each other.
(c) The are concentric lines of force around each conductor
(d) Each of the conductors will move if not prevented from doing so
Answer : B

Question. A small magnet is placed perpendicular to a uniform magnet field. The forces acting on the magnet will result in
(a) Rotational motion
(b) Translatory motion
(c) No motion at all
(d) Translational and rotational motion both
Answer : A

Question. Which one of the following substances is the magnetic substances?
(a) Mercury
(b) Iron
(c) Gold
(d) Silver
Answer : B

Question. Three plotting compasses are placed close to a solenoid carrying a current. How many of the compass needles will change direction, if the current through the solenoid is increased? (Ignore the effect of the earth’s magnetic field).
(a) Only 1 compass needle
(b) 2 compass needle
(c) 3 compass needle
(d) None of the above
Answer : D

Question. The magnetic field at a point due to a current carrying
conductor is directly proportional to the
(a) current flowing through to the
(b) Distance from the conductor
(c) Voltage across the conductor
(d) Resistance of the conductor
Answer : A

Question. Which of the following determines the direction of magnetic field due to a current carrying conductor?
(a) Faraday’s laws of electromagnetic induction
(b) Fleming’s left-hand rule
(c) Lenz’s rule
(d) Maxwell’s cork screw-rule
Answer : D

Question. Choose the correct option (s).
The magnetic field inside a long straight solenoidcarrying 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.
Answer : D

Question. To avoid risk of electrical shock, which phenomena is used?
(a) Over loading
(b) Short circuiting
(c) Earthing
(d) None of these
Answer : C

Question. Force on a current carrying conductor in a magnetic field depends on
(a) direction of the current
(b) direction of magnetic field
(c) Both (a) and (b)
(d) length of the wire
Answer : C

Question. When the bars of bismuth are placed between the magnetic poles they set their length
(a) perpendicular to the lines of force
(b) along the lines of force
(c) neither perpendicular nor along the lines of force
(d) In any direction
Answer : A

Question. The magnetic lines of force, inside a current carrying solenoid, are
(a) along the axis and are parallel to each other
(b) perpendicular to the axis and equidistance from each other
(c) circular and they do not intersect each other
(d) circular at the ends but they are parallel to the axis inside the solenoid.
Answer : A

Question. Magnetic lines do not intersect on one-another because
(a) they are at a distance
(b) they are in the same direction
(c) they are parallel to another
(d) at the point intersection there will be two direction of the magnetic force which is impossible
Answer : D

Question. Who has stated the Right hand Thumb Rule?
(a) Orsted
(b) Fleming
(c) Einstein
(d) Maxwell
Answer :  A

Question. 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
Answer :   C

Question. The factors on which one magnetic field strength produced by current carrying solenoids depends are
(a) Magnitude of current
(b) Number of turns
(c) Nature of core material
(d) All of the above
Answer :   D

Question. 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
Answer :   C

Question. In Fleming’s right hand rule direction in induced current is given by:
(a) thumb
(b) middle finger
(c) first finger
(d) none of these
Answer :   B

Question. We can induce the current in a coil by
(a) moving the coil in a magnetic field
(b) by changing the magnetic field around it
(c) by changing the orientation of the coil in the magnetic field
(d) All of above
Answer :  A

Question. A magnetic field directed in north direction acts on an electron moving in east direction. The magnetic force on the electron will act
(a) vertically upwards.
(b) towards east.
(c) vertically downwards.
(d) towards north.
Answer :   C

Question.   Magnetic effect of current was discovered by
(a) Oersted
(b) Faraday
(c) Bohr
(d) Ampere
Answer :  A

Question. No force acts on a current carrying conductor when it is placed-
(a) perpendicular to the magnetic field
(b) parallel to the magnetic field
(c) far away from the magnetic field
(d) inside a magnetic field
Answer :  B

Question. Which of the following statement is not correct about the magnetic field?
(a) Magnetic field lines form a continuous closed curve.
(b) Magnetic field line do not interest each other.
(c) Direction of tangent at any point on the magnetic field line curve gives the direction of magnetic field at that point.
(d) Outside the magnet, magnetic field lines go from South to North pole of the magnet.
Answer :  D

Question. In the magnetic field the force acting on the current carrying conductor will be maximum :
(a) If conductor is parallel to the field
(b) If conductor is perpendicular to the field
(c) If conductor subtends an angle of 60Deg with the field
(d) If conductor subtends an angle of 45deg with the field
Answer :  A

Question. The direction of induced current is given by
(a) Fleming’s right hand rule
(b) Fleming’s left hand rule
(c) Right hand thumb rule
(d) Left hand thumb rule.
Answer :  A

Question. Electric supply in homes and factories is:
(a) 220V and 400V
(b) 400V and 220V
(c) 220V and 440V
(d) 440V and 220V
Answer : C

Question. AC generator works on the principle of
(a) ohnis law
(b) Joule’s law of heating
(c) faraday’s law of electromagnetic induction.
(d) none of the above
Answer :  C

Question. Induced current flows through a coil 
(a) for more than the period during which flux changes through it.
(b) for less than the period during which flux changes through it.
(c) only for the period during which flux changes through it.
(d) none of the above.
Answer : C

Question. If the force exerted on a current carrying wire placed in a magnetic field is zero, then the angle between wire and the direction of magnetic field is 
(a) 45°
(b) 60°
(c) 90°
(d) 180°
Answer : D

Question. A rectangular coil of copper wires is rotated in a magnetic field. The direction of the induced current change once in each 
(a) two revolutions
(b) one revolution
(c) half revolution
(d) one-fourth revolution.
Answer : C

Question. Four students plotted the sketch of the patterns of magnetic field lines representing the magnetic field around a current carrying straight wire as shown in figures P, Q, R and S. Which one of the following sketches is correct? 

(a) P
(b) Q
(c) R
(d) S
Answer : D

Question. Which of the following properties of a proton can change while it moves freely in a magnetic field? 
(a) Mass
(b) Speed
(c) Momentum
(d) Kinetic energy.
Answer : C

Question. On which of the following does not exert any force when kept in uniform magnetic field? 
(a) Moving magnet
(b) Moving charge
(c) Stationary magnet
(d) Stationary charge
Answer : D

Question. The direction of magnetic field around a straight conductor carrying current can be determined by 
(a) Fleming’s left hand rule
(b) Lenz’s law
(c) Right hand thumb rule
(d) Fleming’s right hand rule.
Answer : C

Question. When is the force experienced by a currentcarrying conductor placed in a magnetic field largest? 
(a) At 30°
(b) at 60°
(c) At 45°
(d) at 90°
Answer : D

Question. An electric motor is a device which transform : 
(a) mechanical anergy to electrical energy
(b) heat energy to electrical energy
(c) electrical energy to heat energy
(d) electrical energy to mechanical energy.
Answer : D

Question. An electric charge in uniform motion produces 
(a) an electric field only
(b) a magnetic field only
(c) both electric and magnetic fields
(d) no such field at all
Answer : C

Question. Three rings P, Q and R are dropped at the same time over identical hollow magnets as shown here. 

Which of the following describes the order in which the ring P, Q and R reach the bottom of the magnet?
(a) They arrive in the order, P, Q, R.
(b) They arrive in the order P, R, Q
(c) Rings P and R arrive simultaneously, followed by Q
(d) Rings Q and R arrive simultaneously, followed by P.
Answer : B

Question. Which of the following instruments works by electromagnetic induction? 
(a) Dynamo.
(b) Moving coil galvanometer.
(c) Telephone receiver.
(d) Simple motor.
Answer : A

Question. 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.
Answer : C

Question. A positively-charged particle (alphaparticle) 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
Answer : D

Question. 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.
Answer : C

Question. Direction of rotation of a coil in electric motor is determined by
(a) fleming’s right hand rule
(b) fleming’s left hand rule
(c) faraday law of electromagnetic inductors
(d) None of above
Answer :  B

Question. Which color wire is used for earthing ?
(a) Red
(b) Blue
(c) Green or yellow
(d) none of these
Answer :  C

Question. Who has stated the Right hand Thumb Rule?
(a) Orsted
(b) Fleming
(c) Einstein
(d) Maxwell
Answer : D

Question. What happens to the current in short circuit?
(a) reduces substantially
(b) does not change
(c) increases heavily
(d) vary continuously
Answer :  C

Question : In India the potential difference between live wire and neutral wire is
(a) 240 V
(b) 250 V
(c) 280 V
(d) 220 V.
Answer :  D

Question. Which among of these are the main characteristics of fuse element?
(a) High conductivity
(b) low melting point
(c) do not bum due to oxidation
(d) All of the above
Answer :  D

Question. On increasing number of turns magnetic field of a solenoid:
(a) Decrease
(b) Increase
(c) no effects
(d) none of these
Answer : B

Question. The magnetic field is the strongest at
(a) middle of the magnet.
(b) north pole.
(c) south pole.
(d) both poles.
Answer :  D

Question. Alnico is an alloy of:
(a) AL, Co, Fe
(b) Mg, Al, Zn, Co
(c) Co, Ni, Al
(d) Al, Ni, Sn
Answer :  C

Question. The strength of magnetic field around a current carrying conductor is
(a) inversely proportional to the current but directly proportional to the square of the distance from wire.
(b) directly proportional to the current and inversely proportional to the distance from wire.
(c) directly proportional to the distance and inversely proportional to the current
(d) directly proportional to the current but inversely proportional the square of the distance from wire.
Answer :  B

Question. The mains power supply of a house is through a 2A fuse. How many 50W bulbs can be used in this house at the normal voltage?
(a) 7
(b) 8
(c) 5
(d) 6
Answer :  B

Question. A magnetic field line is used to find the direction of:
(a) South-north
(b) A compass needle
(c) A bar magnet
(d) Magnetic field
Answer :  D

Question. The most suitable material for making the core of an electromagnet is:
(a) Soft iron
(b) Brass
(c) Aluminium
(d) Steel
Answer :  A

Question. Which of the given correctly describes the magnetic field near a long straight wire?
(a) The field consists of straight lines 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
Answer :  D

Question. Current that does not change its direction after equal intervals of time is called:
(a) direct current
(b) indirect current
(c) Alternating current
(d) Static electricity
Answer :  A

Question. The front face of a circular wire carrying current behaves like a north pole. The direction of current in this face of the circular wire is:
(a) Clockwise
(b) Downwards
(c) Anticlockwise
(d) Upwards
Answer :  C

Question. A rectangular coil of copper wire is rotated in a magnetic field) The direction of induced current changes once in each:
(a) Two revolutions
(b) One revolution
(c) Half revolution
(d) One-fourth revolution
Answer :  C

Question. The frequency of direct current (DC) is:
(a) 0 Hz
(b) 50 Hz
(c) 60 Hz
(d) 100 Hz
Answer :  A

Question. At the time of short circuit the current in the circuit.
(a) reduces substantially
(b) does not change
(c) increases heavily
(d) very continuously.
Answer :  C

Question. Circuit Breaker Device which can be used in place of fuse in domestic electric wiring is called:
(a) CBD
(b) DCB
(c) MCD
(d) MCB
Answer :  D

Question. An electric motor is a device which transforms:
(a) Mechanical energy to electrical energy
(b) Heat energy to electrical only
(c) Electrical energy to heat energy only
(d) Electrical energy to mechanical energy
Answer :  D

Question. A TV set consumes an electric power of 230 watts and runs on 230 volts mains supply. The correct fuse for this TV set is:
(a) Five A
(b) Three A
(c) One A
(d) Two A
Answer :  D

Question. 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
Answer :  D

Question. How many magnetic poles are there in a current carrying solenoid?
(a) two
(b) four
(c) one
(d) six
Answer : A

Fill in The Blank

Question. In a magnetic field pointing away from you, an electron traveling to the right will experience a force in the ......... direction.
Answer : Downward

Question. Field lines are used to represent a ..........
Answer : Magnetic field

Question. In our houses we receive AC electric power of ......... with a frequency of .........
Answer : 220V, 50 Hz.

Question. The N-pole of a compass points to the .......... pole of a permanent magnet.
Answer : S

Question. Field lines are shown closer together where the magnetic field is .........
Answer : Greater

Question. A metallic wire carrying an electric current has associated with it a .......... field.
Answer : Magnetic

Question. Magnetic field lines emerge from the .......... pole of a solenoid or a permanent magnet.
Answer : North

Question. The phenomenon of production of back e.m.f. in a coil due to flow of varying current through it is called ...........
Answer : Self-induction

Question. A Permanent behaves like a solenoid because both contain currents in the form of ..........
Answer : Circles

Question. Field lines come out of ......... pole while enters from ........... pole.
Answer : North, South

True/False

Question. The induced e.m.f. depends only the turns of the coil.
Answer : False

Question. Fleming’s left hand rule helps us to find the direction of the induced current.
Answer : False

Question. The direction of force on a current carrying conductor placed in a magnetic field cannot be reversing the direction of magnetic field.
Answer : False

Question. The magnitude of induced current can be decreased by increasing the area of cross. section of coil.
Answer : False

Question. An electron does not suffer any deflections while passing through a region. This makes sure that there is no magnetic field in that region.
Answer : True

Question. Energy associated with an electric field is analogous to potential energy whereas the energy associated with the magnetic field is analogous to kinetic energy.
Answer : True

Question. A magnetic field exists in the region surrounding a magnet, in which the force of the magnet can be detected.
Answer : True

Question. An electric generator works on the principle of electromagnetic induction.
Answer : True

Assertion and Reason

DIRECTION : In the following questions, a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as:
(a) Both assertion (A) and reason (R) are true and reason (R) is the correct explanation of assertion (A).
(b) Both assertion (A) and reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(c) Assertion (A) is true but reason (R) is false.
(d) Assertion (A) is false but reason (R) is true.
(e) Both Assertion and Reason are false.

Question. Assertion : An induced e.m.f. appears in any coil in which the current is changing.
Reason : Self induction phenomenon obeys Faraday’s law of induction.
Answer : B

Question. Assertion : A solenoid tends to expand, when a current passes through it.
Reason : Two straight parallel metallic wires carrying current in same direction attract each other.
Answer : D

Question. Assertion : Safety fuses are made up of materials having a low melting point.
Reason : Safety fuses should be resistant to electric current.
Answer : C

Question. Assertion : AC load line is used for long distance transmission.
Reason : It has very less loss of energy in long distance transmission.
Answer : A

Question. Assertion : Copper is used to make electric wires.
Reason : Copper has very low electrical resistance.
Answer : A

Question. Assertion : When two bulbs are operated on same voltage supply, having power 60W and 100W then 100W bulb has less resistance than 60W.
Reason : The power of the bulb is directly proportional to the square of the voltage.
Answer : B

Question. Assertion : The magnetic field produced by a current carrying solenoid is independent of its length and cross-section area.
Reason : The magnetic field inside the solenoid is uniform.
Answer : B

Question : SI unit of magnetic field strength is