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

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#1. 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.

Forces both pointing into the plane of paper

Forces both pointing out of the plane of paper

Forces pointing into the plane of paper and out of the plane of paper, respectively

Force pointing opposite and along the direction of the uniform magnetic field respectively

Explanation: Direction of current is taken as opposite to the flow of electron or in the direction of flow of protons.

In the given figure, the proton and electron are moving in opposite direction to each other and in perpendicular to the direction of magnetic field. So, current due to both electron and proton are in same direction. Hence, the forces acting on both will be in the same direction. By Fleming’s left hand rule the direction, force is pointing into the plane of paper.

#2. 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.

#3. 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.

#4. At the time of short circuit, the current in the circuit

Reduces substantially.

Does not change.

Increases heavily.

Vary continuously.

#5. 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.

#6. A D.C generator works on the principle of

ohm's law

Joule’s law of heating

faraday’s law of electromagnetic induction.

none of the above

Explanation: electric generator works on the basis of electromagnetic induction.

#7. 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.

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

will become zero.

will increase.

will decrease.

will remain unaffected.

#9. An electric generator actually acts as

a source of electric charge.

a source of heat energy.

an electromagnet.

a converter of energy.

#10. A positive charge is moving upwards in a magnetic field directed towards north. The particle will be deflected towards

west

north

south

east

Explanation: (a) Apply fleming’s left hand rule

#11. 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.

#12. Who has stated the Right hand Thumb Rule?

Orsted

Fleming

Einstein

Maxwell

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

aluminum

soft iron

copper

steel

#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. Commercial electric motors do not use

an electromagnet to rotate the armature

effectively large number of turns of conducting wire in the current carrying coil

a permanent magnet to rotate the armature

a soft iron core on which the coil is wound

Explanation: Using electromagnet, the magnetic field strength further increase by increasing the current. Hence it will enhance the power of electric.

#16. A.C generator works on the principle of

force experience by a conductor in magnetic field

electromagnetic induction

electrostatic

force experience by a charge particle in electric field.

Explanation: Generator works on principle of electromagnetic induction.

#17. Earth wire carries

current

voltage

no current

heat

Explanation: Earth wire carries no current.

#18. 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

#19. The instrument that use to detect electric current in the circuit is known as

electric motor

A.C generator

galvanometer

none of the above

Explanation: A galvanometer is an instrument that can direct the presence of current in a circuit.

#20. 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.

#21. 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.

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

Geographical South

Geographical East

Geographical West

Geographical North

#23. An electric motor is a device which transforms

Mechanical energy into electrical energy

Electrical energy into mechanical energy

Kinetic energy into potential energy

Electrical energy into Potential energy

#24. Which of the following statement is not correct about the magnetic field?

Magnetic field lines form a continuous closed curve.

Magnetic field line do not interest each other.

Direction of tangent at any point on the magnetic field line curve gives the direction of magnetic field at that point.

Outside the magnet, magnetic field lines go from South to North pole of the magnet.

Explanation:
(d) Outside the magnet, magnetic field line emerges from North-pole and moves towards south-pole.

#25. A current carrying conductor is held in exactly vertical direction. In order to produce a clockwise magnetic field around the conductor, the current should be passed in the conductor:

From top to bottom

From left to right

From bottom to top

From right to left

finish