Tag: physics

Quizzes (598) Questions (13441)

Questions Related to physics

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

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 ?

  1. <span>downwards.</span>

  2. <span>upwards.</span>

  3. <span>towards right&nbsp;</span>

  4. <span>towards left&nbsp;</span>
Reveal answer Fill a bubble to check yourself
A Correct answer
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.
Multiple choice physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

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

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
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.

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

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:

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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?

  1. An upward force.

  2. A downward force.

  3. A force to the left.

  4. No force is felt.
Reveal answer Fill a bubble to check yourself
D Correct answer
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.
Multiple choice physics magnetic effect of electric current fleming's left hand rule magnetic force magnetic force on a moving charge and current carrying wire

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

  1. Fleming's Left Hand Rule

  2. Fleming's Right Hand Rule

  3. End Rule

  4. Right Hand Palm Rule
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  1. towards right

  2. towards left

  3. upwards

  4. downwards
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

In _______ Fleming Left hand rule is not used.

  1. Electric fan

  2. Mixer

  3. Computer

  4. Electric generator
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Fleming's left-hand rule is used for electric motors, which convert electrical energy into mechanical energy. An electric generator uses Fleming's right-hand rule, as it converts mechanical energy into electrical energy.

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

An electron is moving vertically downwards at any place. The direction of magnetic force acting on it due to horizontal component of earth's magnetic field will be

  1. towards east

  2. towards west

  3. towards north

  4. towards south
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to Fleming left hand rule, if the direction of horizontal component of earth's magnetic field is from south to north and direction of velocity of electron is downwards then the direction of the force given by the thumb is towards west.

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

An electron and a proton travel with equal speeds and in the same direction, at $90^o$ to a uniform magnetic field. They experience forces which are initially

  1. in opposite direction and differ by a factor of about 1840

  2. in the same direction and differ by a factor of about 1840

  3. equal in magnitude but in opposite directions

  4. identical
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation
As both of the particle having same speed and in the same field at same angle, they will be experiencing same force but in opposite direction as they are opposite in charge.