Tag: magnetic force

Questions Related to magnetic force

An electron having a charge e moves with a velocity v in X-direction. A magnetic field acts on it in Y-direction. The force on the electron acts in

physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

  1. positive direction of Y-axis

  2. negative direction of Y-axis

  3. positive direction of Z-axis

  4. negative direction of Z-axis

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Correct Option: D
Explanation:
As electron moving in positive x-direction, so the current  is moving in negative x-direction ( the direction of your middle finger) and the magnetic field acts on positive Y-direction ( the direction of your index finger) then thumb will be in negative Z-direction which is the direction of force. 

A positively charged particle falls vertically downwards. The horizontal component of earths magnetic field will deflect it towards

physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

  1. West

  2. East

  3. South

  4. North

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Correct Option: B

You are sitting in a room in which a strong magnetic field is directed from your left towards right. A beam of electrons is directed from front towards you. What would be the direction of magnetic force on this beam ?

physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

  1. downwards.

  2. upwards.

  3. towards right 

  4. towards left 

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Correct Option: A
Explanation:
The direction of the magnetic field is from left to right, the direction of the beam of electrons is from your front hence the direction of the current is from back to front. Now by applying Fleming left hand rule we can find that the direction of the magnetic force on the beam of electron is downwards.

An electron is travelling along the x-direction. It encounters a magnetic field in the ydirection. Its subsequent motion will be

physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

  1. straight line along the x-direction

  2. a circle in the zx-plane

  3. a circle in the yz-plane

  4. a circle in the xy-plane

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Correct Option: B
Explanation:

The magnetic force acting on a charged particle is given by 

$\vec{F}=q(\vec{v}\times \vec{B})$
Hence direction of force acting one electron is $\hat{i}\times \hat{j}=\hat{k}$
The force experienced is in z-direction. So the particle moves in the zx plane.

An electric current runs counterclockwise in a rectangular loop around the outside edge of the page which lies flat on your table. A uniform magnetic field is then turned on directed parallel to the page from the top to bottom. The magnetic force on the page will cause:

physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

  1. the left edge to lift up

  2. the right edge to lift up

  3. the top edge to lift up

  4. the bottom edge to lift up

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Correct Option: C
Explanation:

Current is flowing anticlockwise in the rectangular loop and in the upper edge of page current is flowing towards left and magnetic field is from top to bottom , so by applying Fleming's left hand rule the direction of force is found to be in the upward direction, lifting the top edge up.

A positive charge is at rest in a uniform magnetic field directed to the right. What force does the positive charge feel, due to the magnetic field?

physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

  1. An upward force.

  2. A downward force.

  3. A force to the left.

  4. No force is felt.

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Correct Option: D
Explanation:
For experiencing a magnetic force on a charge  particle, the particle should move in the magnetic field with some velocity. As the velocity of the particle is zero so, the force on the particle is also zero.

The direction of force on a current carrying conductor placed in a magnetic field is given by :

physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

  1. Fleming's Left Hand Rule

  2. Fleming's Right Hand Rule

  3. End Rule

  4. Right Hand Palm Rule

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Correct Option: A
Explanation:

The direction of this force is always right angles to the plane containing both the conductor and the magnetic field, and is predicted by Fleming’s Left-Hand Rule.

A vertical wire carries a current in upward direction. An electron beam sent horizontally towards the wire will be deflected (gravity free space) :

physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

  1. towards right

  2. towards left

  3. upwards

  4. downwards

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Correct Option: C
Explanation:

$F= q(\vec{v} \times \vec{B})= (-e)( -v\hat{i}\times (-B\hat{k}))=evB\hat{j}$
Thus, force on the electron beam is along the +ve y-axis.

In _______ Fleming Left hand rule is not used.

physics magnetic fields and electromagnetism fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

  1. Electric fan

  2. Mixer

  3. Computer

  4. Electric generator

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Correct Option: D

Fleming's left hand rule is used to find

physics magnetic fields and electromagnetism fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

  1. Direction of magnetic field 

  2. Direction of current

  3. Direction of magnetic force acting on conductor

  4. None of these

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Correct Option: A