Which one of the following substances is the magnetic substances?
Mercury
Iron
Gold
Silver
(2)
Among the given substances, the iron is the only magnetic substances.
The magnetic lines of force, inside a current carrying solenoid are:
Along the axis and are parallel to each other
Perpendicular to axis and equidistant from each other
Circular and they do not intersect each other
Circular at the ends but they are parallel to the axis inside the solenoid
(1)
The figure shows the magnetic lines of forces the solenoid.
In the diagram shown below, what is the component A:
Solenoid
Glass rod
Magnetic material
None of these
(3)
Here, A is a magnetic material on which solenoid as wrapped. As by passing current through it the magnetic material will become an electromagnet.
Which of the following determine the direction of magnetic field due to a current carrying conductor?
Faraday's laws of electromagnetic induction
Fleming's left hand rule
Lenz's law
Maxwell's cork screw-rule
(4)
According to Maxwell's Cork Screw-Rule, if we consider ourselves driving a cork screw in the direction of current, then the direction of the rotation of cork Screw is the direction of the Magnetic field.
Which of the following is not an example of the right hand thumb rule?
D.C. motor
Solenoid
A.C. generator
Cartesian coordinate system
(4)
Cartesian Coordinate system is not an example of the right-hand thumb rule. The cartesian coordinate system is used for representing points in space using three perpendicular axes (X, Y and Z). It does not involve any magnetic field, current or force so the right-hand thumb rule does not apply here.
Commercial 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
(3)
Commercial motors do not use permanent magnets because they are weak and do not produce strong magnetic field in the region.
The process of inducing a current in a coil of wire by placing it in a region of changing magnetic field is:
Electrical effect
Heating effect of current
Magnetic effect of current
Electromagnetic induction
(4)
The process of inducing a current in a coil of wire by placing it in a region of changing magnetic field is electromagnetic induction.
The core of electromagnet is made of:
soft iron
steel
magnesium
copper
(1)
The core of electromagnet is made of soft iron due to following reasons:
(i) It can be easily magnetised and demagnetised.
(ii) It has low carbon content.
(iii) It has large susceptibility and small retentivity.
(iv) It does not retain its magnetism when the current is switched off.
(v) It is less corrosive.
Fleming's Right-hand rule gives:
Magnitude of the induced current.
Magnitude of the magnetic field.
Direction of the induced current.
Both, direction and magnitude of the induced current.
(3)
Fleming's Right hand rule gives the direction of the induced current.
Stretch the thumb, forefinger and middle finger of right hand so that they are perpendicular to each other. If forefinger indicates the direction of the magnetic field, thumb shows the direction of motion of conductor, then the middle finger will show the direction of induced current. We cannot find out the magnitude of either the induced current or magnetic field by this law.
Which of the following property of a proton can change while it moves freely in a magnetic field?
Mass
Speed
Velocity
Charge
(3)
Velocity of a proton can change while it moves freely in a magnetic field because each moving charged particle in a magnetic field experiences a force. The direction of force experienced by a positively charged proton can be studied by Fleming’s Left-hand Rule.
The force acting on the proton would change both velocity and momentum when it moves freely in magnetic field. If a charged particle’s velocity is completely parallel to the magnetic field, the magnetic field will not exert any force on the particle, and thus the velocity will remain constant. Whereas, if the force is acting perpendicular to the direction of moving charge, work done will be zero. It means kinetic energy does not change. Hence, we can conclude that the force can change the direction of velocity of the proton but not its speed. Thus, momentum and velocity changes.
