CN202084230U - Earth magnetic field motional electromotive force experimental instrument - Google Patents

Abstract

An earth magnetic field motional electromotive force experimental instrument belongs to the field of physical experiments, is composed of a conductor rod (5), a small magnetic needle (3), a support (2) and a millvoltmeter (7), and is characterized in that the plane of the rectangular support (2) passes through the centre of a base plate (1) horizontally arranged and is vertically fixed on the base plate (1); the rotating shaft of the small magnetic needle (3) passes through the centre hole of slim straight rods (6) and is fixed at the centre of the base plate (1); a horizontal rotating shaft (4) perpendicular to the support (2) is fixed at a position of the support above the small magnetic needle (3), the conductor rod (5) with a punched end is suspended on the horizontal rotating shaft (4), the conductor rod (5) can freely swing in a plane parallel with the support (2), and the punched end of the conductor rod (5) and a flexible lead (8) are connected to the voltage input port of the millvoltmeter (7). The experimental instrument realizes a new method for demonstrating the motional electromotive force by automatically changing the moving speed of a conductor in an earth magnetic field.

Description

A kind of terrestrial magnetic field motional electromotive force experiment instrument

Technical field

The utility model patent relates to the experimental apparatus of demonstrating motional electromotive force, belongs to the physical experiment apparatus field.

Background technology

Motional electromotive force is a very important content in physics and related discipline teaching, in the past lecture experiment mostly in the magnetic field that magnet produces conductor do cutting magnetic line movement and produce electromotive force, space is limited should not be observed because conductor length is lacked, for making good demonstration effect, need enough strong magnet to demonstrate, the bad control of conductor motion speed, the direction of motion of conductor also needs human intervention, we usually mention the problem in uniform magnetic field in teaching material and relevant issues discussion, there is not corresponding experimental apparatus, experimental apparatus needs redesign, the direction of motion and the velocity magnitude that how to be implemented in the uniform magnetic field lower conductor change automatically, can well demonstrate some contents of motional electromotive force.And the experimental apparatus that cost is low, simple and easy to operate, this patent will address this problem.

Summary of the invention

The utility model patent solves the experimental apparatus of demonstration motional electromotive force, and the conductor of solution in uniform magnetic field changes the experimental provision of direction of motion and velocity magnitude generation motional electromotive force automatically emphatically.

The utility model patented technology scheme: a kind of terrestrial magnetic field motional electromotive force experiment instrument, be to constitute by conductor rods, small magnetic needle, support and milivoltmeter etc., it is characterized in that: on the chassis of horizontal positioned, center and the chassis of the plane of rectangle support being crossed the chassis are vertically fixing; The center pit that thin straight-bar is passed in the rotating shaft of small magnetic needle (compass) be fixed on the chassis in the heart, thin straight-bar can freely rotate on the surface on chassis, allows the parallel terrestrial magnetic field direction of representing of thin straight-bar and small magnetic needle sensing during experiment; A horizontal rotating shaft perpendicular to support is fixed at support place corresponding directly over the small magnetic needle, the conductor rods of one end punching is suspended on the horizontal rotating shaft, conductor rods can freely swing in being parallel to the perpendicular of support, and the punching end of conductor rods and a flexible wire are connected the voltage input interface of milivoltmeter.During experiment, adjust the angle of support plane and small magnetic needle sensing by rotating chassis, rotating thin straight-bar points to parallel with small magnetic needle, the direction of thin straight-bar is represented magnetic direction, the plane of movement of conductor rods is represented on the support plane, the pull-up conductor rods discharges, and just can observe the electromotive force size and Orientation of swinging along with conductor rods by milivoltmeter.

Be difficult to form bigger uniform magnetic field space under the common lab condition, we find that the earth of living is exactly a very stable magnetic field space, and magnetic field is even at the earth's surface, according to the motional electromotive force formula

$\mathrm{\ϵ}={\∫}_L(\stackrel{\→}{v}\×\stackrel{\→}{B})\·d\stackrel{\→}{l}$

As accompanying drawing 1, be L for the conductor length of swinging near the at the earth's surface perpendicular, quality is m, earth induction intensity is

Instantaneous conductor infinitesimal dl movement velocity

With

Angle

Angle of oscillation speed is ω, and then the direction of motional electromotive force can be judged by right-hand rule, and size is

If conductor is I to the moment of inertia of axle, discharging pivot angle (conductor and vertical curve angle) at first is θ ₀, ignore friction and air damping, instantaneous pivot angle is θ, consider the conductor swinging plane with

Angle

Measure easily with θ,

With

Represent with θ, by geometric relationship

${\left(\stackrel{\‾}{a}b\right)}^2={\left(\stackrel{\‾}{\mathrm{bc}}\right)}^2+{\left(\stackrel{\‾}{a}c\right)}^2,$

Draw

ω is by rigid body mechanical energy theorem

$\frac{1}{2}I{\mathrm{\ω}}^2=\mathrm{mg}\frac{L}{2}(\cos \mathrm{\θ}-\cos {\mathrm{\θ}}_0)$

Decision, the simultaneous following formula draws

If the moment of inertia of conductor rods is

Draw

Like this, the electromotive force size is with conductor swinging plane and magnetic induction density

The orientation angle

And the physical quantitys such as pivot angle θ of conductor have been set up physical relationship.

The design of the utility model patent is easy to realize, cost is low, easy to operate, when conductor rods is 1 meter long experiment, just clearly observe the size and the direction of electromotive force, be implemented in the uniform magnetic field zone, realized that by freely swinging of conductor rods the automatic change of conductor direction of motion and velocity magnitude demonstrates the new method of motional electromotive force, phenomenon is obvious.In teaching, use the student is had more evocation.

Description of drawings

Accompanying drawing 1 is the principle schematic of the utility model patent.

Accompanying drawing 2 is the synoptic diagram of experimental provision.Wherein: the 1st, chassis, the 2nd, rectangle support, the 3rd, small magnetic needle (compass), the 4th, horizontal rotating shaft, the 5th, conductor rods, the 6th, thin straight-bar, the 7th, milivoltmeter, the 8th, connecting line

Embodiment

As accompanying drawing, on the chassis (1) of horizontal positioned, center and chassis (1) of the plane of rectangle support (2) being crossed chassis (1) are vertically fixing; The center pit that thin straight-bar (6) is passed in the rotating shaft of small magnetic needle (compass) (3) be fixed on chassis (1) in the heart, thin straight-bar (6) surface of (1) can freely rotate on the chassis; Support (2) corresponding directly over the small magnetic needle (3) locates to fix a horizontal rotating shaft perpendicular to support (2) (4), the conductor rods (5) of one end punching is suspended on the horizontal rotating shaft (4), conductor rods (5) can freely swing in the perpendicular that is parallel to support (2), and the punching end of conductor rods (5) and a flexible wire (8) are connected the voltage input interface of milivoltmeter (7).

Claims (1)

1. terrestrial magnetic field motional electromotive force experiment instrument, be by conductor rods (5), small magnetic needle (3), support (2) and milivoltmeter formations such as (7), it is characterized in that: on the chassis (1) of horizontal positioned, center and chassis (1) of the plane of rectangle support (2) being crossed chassis (1) are vertically fixing; The center pit that thin straight-bar (6) is passed in the rotating shaft of small magnetic needle (3) be fixed on chassis (1) in the heart; Support (2) corresponding directly over the small magnetic needle (3) locates to fix a horizontal rotating shaft perpendicular to support (2) (4), the conductor rods (5) of one end punching is suspended on the horizontal rotating shaft (4), conductor rods (5) can freely swing in the plane that is parallel to support (2), and the punching end of conductor rods (5) and a flexible wire (8) are connected the voltage input interface of milivoltmeter (7).

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