## Questions about magnetic field,emergency snow kit for car,safety tips for thunderstorms hurricanes and tornadoes - Try Out

Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. The magnetic fields in question are generated by the motion of charged gas in the accretion disk i.e. The literature contains references to the field lines threading the event horizon, but I suspect this is just rather casual wording.
It has long been known that active galaxy nuclei possess a strong magnetic field, but what is new is the realisation of just how strong these fields are.
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If you are carrying a magnet, can you tell when you cross the event horizon of a black hole?
When reviewing a manuscript for the second time, is it fair to comment on aspects I did not realise the first time? To experience the Kshitij Education India - Quality, attend our Free Demo and get IITians to teach you from the comfort of your home. In our study of electricity, we described the interactions between charged objects in terms of electric fields.
Historically, the symbol B has been used to represent a magnetic field, and this is the notation we use in this text. We can define a magnetic field B at some point in space in terms of the magnetic force FB that the field exerts on a test object, for which we use a charged particle moving with a velocity v. The magnitude FB of the magnetic force exerted on the particle is proportional to the charge q and to the speed ν of the particle. The magnitude and direction of FB depend on the velocity of the particle and on the magnitude and direction of the magnetic field B.

When a charged particle moves parallel to the magnetic field vector, the magnetic force acting on the particle is zero. The magnetic force exerted on a positive charge is in the direction opposite the direction of the magnetic force exerted on a negative charge moving in the same direction (Fig. Figure 29.4 reviews the right-hand rule for determining the direction of the cross product v x B. The electric force acts in the direction of the electric field, whereas the magnetic force acts perpendicular to the magnetic field. The electric force acts on a charged particle regardless of whether the particle is moving, whereas the magnetic force acts on a charged particle only when the particle is in motion.
The electric force does work in displacing a charged particle, whereas the magnetic force associated with a steady magnetic field does no work when a particle is displaced. From the last statement and on the basis of the workâkinetic energy theorem, we conclude that the kinetic energy of a charged particle moving through a magnetic field cannot be altered by the magnetic field alone.
A non-SI magnetic-field unit in common use, called the gauss (G), is related to the tesla through the conversion 1 T = 104 G.
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Real black holes do not contain a true horizon as the true horizon takes an infinite coordinate time to develop. The direction of the magnetic field B at any location is the direction in which a compass needle points at that location. For the time being, let us assume that no electric or gravitational fields are present at the location of the test object.
We can regard this equation as an operational definition of the magnetic field at some point in space.

You point the four fingers of your right hand along the direction of v with the palm facing B and curl them toward B.
In other words, when a charged particle moves with a velocity v through a magnetic field, the field can alter the direction of the velocity vector but cannot change the speed or kinetic energy of the particle.
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So it is not the case that the black hole generates the magnetic field which then has to somehow escape through the event horizon.
In addition to an electric field, the region of space surrounding any moving electric charge also contains a magnetic field. Figure 29.1 shows how the magnetic field of a bar magnet can be traced with the aid of a compass. That is, the magnetic field is defined in terms of the force acting on a moving charged particle.
The extended thumb, which is at a right angle to the fingers, points in the direction of v x B. It isn't clear to me whether magnetic fields can thread an apparent horizon, but in any case the field lines will become very distorted in the immediate vicinity of the horizon and the end result will be essentially identical to the field lines threading the horizon. Note that the magnetic field lines outside the magnet point away from north poles and toward south poles.
One can display magnetic field patterns of a bar magnet using small iron filings, as shown in Figure 29.2.