CBSE X Science Magnetic Effects of Current - EducareHut (Next Gen Knowledge Point)

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#1. The strength of each of magnet reduces to half when it cut along its length into the equal parts magnetic field strength of a solenoid. Polarity of solenoid can be determined by

use of compass needle

Right hand thumb rule

fleming left hand rule

either (a) or (b)

Explanation: (d) both (a) and (b) can be use to determine the polarity of solenoid.

#2. The frequency of electricity produced by DC generator is equal to

0 Hz

50 Hz

100 Hz

200 Hz

#3. Which of the following factors affect the strength of force experience by a current carrying conduct in a uniform magnetic field?

magnetic field strength

magnitude of current in a conductor

length of the conductor within magnetic field

All of the other 3 Answers.

Explanation: (d) All the factors affect the strength of magnetic force.

#4. Magnetic lines of force inside current carrying solenoid are

perpendicular to axis.

along the axis and are parallel to each other.

parallel inside the solenoid and circular at the ends.

circular.

#5. An induced emf is produced when a magnet is moved into a coil. The magnitude of induced emf does not depend on:

The speed with which the magnet is moved

The number of turns of the coil

The resistivity of the wire of the coil

The strength of the magnet

#6. If the key in the arrangement as shown is taken out (the circuit is made open) and magnetic field lines are drawn over the horizontal plane ABCD, the lines are

Concentric circles

Elliptical in shape

Straight lines parallel to each other

Concentric circles near the point O but of elliptical shapes as we go away from it

Explanation: If key is taken out then current will stop and no magnetic field exists due to the conductor. Therefore, at the point O, there will be earth’s magnetic field and they will be straight lines parallel to each other.

#7. The essential difference between an AC generator and a DC generator is that

AC generator has an electromagnet while a DC generator has permanent magnet.

DC generator will generate a higher voltage.

AC generator will generate a higher voltage.

AC generator has slip rings while the DC generator has a commutator.

#8. A coil of insulated copper wire is connected to a galvanometer forming a loop and a magnet id. A: Held stationary B: Moved away along its axis C: Moved towards along its axis.There will be a induced current in:

A only

A and B only

B and C only

A, B and C

#9. We can induce the current in a coil by

moving the coil in a magnetic field

by changing the magnetic field around it

by changing the orientation of the coil in the magnetic field

All of above

#10. A soft iron bar is inserted inside a current-carrying solenoid. The magnetic field inside the solenoid:

Will decrease

Will increase

Will become zero

Will remain the same

#11. In electric motor, to make the coil rotating continuously in the same direction, current is reversed in the coil after every half rotation by a device called

carbon brush

commutator

slip ring

armature

Explanation: (b) A device that reverses the direction of current in the arms of armature through a circuit is called commutation.

#12. The device used for producing electric current is called a

Generator.

Galvanometer.

Ammeter.

Motor.

#13. The north pole of Earth’s magnet is in the:

Geographical South

Geographical East

Geographical West

Geographical North

#14. A magnetic field directed in north direction acts on an electron moving in east direction. The magnetic force on the electron will act

vertically upwards.

towards east.

vertically downwards.

towards north.

#15. A soft iron bar is introduced inside the current carrying solenoid. The magnetic field inside the solenoid

will decrease

will remains same

will increase

will become zero

Explanation: (c) Soft iron inside the current carrying solenoid act as an electromagnet.

#16. A magnet is moved towards a coil (i) quickly (ii) slowly. The induced potential difference

#17. Inside the magnet, the field lines moves

from north to south

from south the north

away from south pole

away from north pole

Explanation:
(a) Magnetic field inside the magnet moves from south to north pole.

#18. The factors on which one magnetic field strength produced by current carrying solenoids depends are

Magnitude of current

Number of turns

Nature of core material

All of the other 3 answers

Explanation: (d) Factors shown in (a), (b) and (c).

#19. The condition for the phenomena of electromagnetic induction is that there must be a relative motion between

the galvanometer and magnet

the coil of wire and galvanometer

the coil of wire and magnet

the magnet and galvanometer

Explanation: (c) The relative motion between the magnet and coil of wire causes change in magnetic field lines linked with the coil to produces induced current if the circuit is closed.

#20. The most important safety method used for protecting home appliances from short circuiting or overloading is

Earthing

Use of fuse

Use of stabilizers

Use of electric meter

Explanation: Use of electric fuse is the most important method used for protecting home appliances from short-circuiting or overloading.

Generally, thin wire with low melting having specific rating is connected in series with the electric devices. When the current passing through the fuse exceeds a specific value then by heating effect of current it melts and breaks the circuit.

#21. The nature of magnetic field line passing through the centre of current carrying circular loop is

circular

ellipse

parabolic

straight line

Explanation:(d) magnetic field line at the centre of current carrying loop appears as a straight line.

#22. When current is parallel to magnetic field, then force experience by the current carrying conductor placed in uniform magnetic field is

Twice to that when angle is 60°

Thrice to that when angle is 60°

zero

infinite

Explanation: (a) If the current direction is parallel to the magnetic field, then there will no force on the conductor exerted by the magnetic field.

#23. The strength of magnetic field around a current carrying conductor is

inversely proportional to the current but directly proportional to the square of the distance from wire.

directly proportional to the current and inversely proportional to the distance from wire.

directly proportional to the distance and inversely proportional to the current

directly proportional to the current but inversely proportional the square of the distance from wire.

Explanation:
• Magnetic field strength increases on increasing the current through the wire.
• Magnetic field strength decreases as the distance from the wire increases.

#24. A fuse should always be placed in the

Live wire of the main circuit

Neutral wire of the main circuit

Earth wire of the main circuit

Both live and neutral wire of the main circuit.

#25. Material of the core of a strong magnet is

aluminum

soft iron

copper

steel

finish