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Theatre Production Join us Nov. Show Search Bar:. Magnetic poles always occur in pairs of north and south—it is not possible to isolate north and south poles. Conceptual Questions Discuss the similarities and differences between the electrical force on a charge and the magnetic force on a charge. Both are field dependent.
Electrical force is dependent on charge, whereas magnetic force is dependent on current or rate of charge flow. What is the direction of the magnetic force on a positive charge that moves as shown in each of the six cases? What is the direction of the velocity of a negative charge that experiences the magnetic force shown in each of the three cases, assuming it moves perpendicular to B?
What is the direction of the magnetic field that produces the magnetic force on a positive charge as shown in each of the three cases, assuming is perpendicular to? Suppose a supersonic jet has a 0. What are the direction and the magnitude of the magnetic force on the plane? The force is very small, so this implies that the effect of static charges on airplanes is negligible. An electron moving at in a 1. There are two answers. Skip to content Magnetic Forces and Fields.
Learning Objectives By the end of this section, you will be able to: Define the magnetic field based on a moving charge experiencing a force Apply the right-hand rule to determine the direction of a magnetic force based on the motion of a charge in a magnetic field Sketch magnetic field lines to understand which way the magnetic field points and how strong it is in a region of space. Defining the Magnetic Field A magnetic field is defined by the force that a charged particle experiences moving in this field, after we account for the gravitational and any additional electric forces possible on the charge.
Magnetic fields exert forces on moving charges. The direction of the magnetic force on a moving charge is perpendicular to the plane formed by and and follows the right-hand rule-1 RHR-1 as shown. The magnitude of the force is proportional to and the sine of the angle between and.
What is the magnetic force on the alpha-particle when it is moving a in the positive x -direction with a speed of b in the negative y -direction with a speed of c in the positive z -direction with a speed of d with a velocity The magnetic forces on an alpha-particle moving in a uniform magnetic field. The field is the same in each drawing, but the velocity is different.
Representing Magnetic Fields The representation of magnetic fields by magnetic field lines is very useful in visualizing the strength and direction of the magnetic field. Magnetic field lines have several hard-and-fast rules: The direction of the magnetic field is tangent to the field line at any point in space.
A small compass will point in the direction of the field line. Note that the symbols used for the field pointing inward like the tail of an arrow and the field pointing outward like the tip of an arrow. Extensive exploration of magnetic fields has revealed a number of hard-and-fast rules. We use magnetic field lines to represent the field the lines are a pictorial tool, not a physical entity in and of themselves. The properties of magnetic field lines can be summarized by these rules:.
The last property is related to the fact that the north and south poles cannot be separated. It is a distinct difference from electric field lines, which begin and end on the positive and negative charges. If magnetic monopoles existed, then magnetic field lines would begin and end on them. Skip to main content. Search for:. Magnetic Fields and Magnetic Field Lines Learning Objective By the end of this section, you will be able to: Define magnetic field and describe the magnetic field lines of various magnetic fields.
Making Connections: Concept of a Field A field is a way of mapping forces surrounding any object that can act on another object at a distance without apparent physical connection. The field represents the object generating it. Magnetic fields, no matter how complicated they are, do not have any ends. These magnetic fields are very important since they exert an influence on other objects. As we said before, magnets always attract objects made out of iron.
In order to see this, put a magnet near a nail made out of iron and watch as the magnet pulls the nail toward it? Notice that as you move the magnet closer to the nail the attraction between the nail and the magnet becomes stronger. If you move the magnet further away from the nail the attraction becomes weaker until the moment when the nail stops to be attracted altogether.
That's because at some point the nail entered the magnetic field of the magnet and was attracted toward the magnet by the magnetic force. We say that the magnetic field exerts a magnetic force on the nail. The strength of this force depends on the distance between the magnet and the nail.
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