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प्रश्न
An electron travelling west to east enters a chamber having a uniform electrostatic field in north to south direction. Specify the direction in which a uniform magnetic field should be set up to prevent the electron from deflecting from its straight line path.
उत्तर
An electron travelling from West to East enters a chamber having a uniform electrostatic field in the North-South direction. This moving electron can remain undeflected if the electric force acting on it is equal and opposite of the magnetic field. Magnetic force is directed towards the South. According to Fleming’s left-hand rule, a magnetic field should be applied in a vertically downward direction.
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संबंधित प्रश्न
(a) Write the expression for the magnetic force acting on a charged particle moving with velocity v in the presence of magnetic field B.
The free electrons in a conducting wire are in constant thermal motion. If such a wire, carrying no current, is placed in a magnetic field, is there a magnetic force on each free electron? Is there a magnetic force on the wire?
- If v is parallel to B, then path of particle is spiral.
- If v is perpendicular to B, then path of particle is a circle.
- If v has a component along B, then path of particle is helical.
- If v is along B, then path of particle is a circle.
Consider a wire carrying a steady current, I placed in a uniform magnetic field B perpendicular to its length. Consider the charges inside the wire. It is known that magnetic forces do no work. This implies that ______.
- motion of charges inside the conductor is unaffected by B since they do not absorb energy.
- some charges inside the wire move to the surface as a result of B.
- if the wire moves under the influence of B, no work is done by the force.
- if the wire moves under the influence of B, no work is done by the magnetic force on the ions, assumed fixed within the wire.
A cubical region of space is filled with some uniform electric and magnetic fields. An electron enters the cube across one of its faces with velocity v and a positron enters via opposite face with velocity – v. At this instant ______.
- the electric forces on both the particles cause identical accelerations.
- the magnetic forces on both the particles cause equal accelerations.
- both particles gain or loose energy at the same rate.
- the motion of the centre of mass (CM) is determined by B alone.
A 100 turn rectangular coil ABCD (in XY plane) is hung from one arm of a balance (Figure). A mass 500 g is added to the other arm to balance the weight of the coil. A current 4.9 A passes through the coil and a constant magnetic field of 0.2 T acting inward (in xz plane) is switched on such that only arm CD of length 1 cm lies in the field. How much additional mass ‘m’ must be added to regain the balance?
A unit vector is represented as `(0.8hat"i" + "b"hat"j" + 0.4hat"k")`. Hence the value of 'b' must be ______.
Lorentz force in vector form is ______.
