" Ding December " bell rang , the students happily prepare science lessons. I have in mind : What an interesting experiment today, it ? ( At the beginning of suspense , readers' interest . )
At
this time , the teacher walked toward the podium, smiling, said:
"Students, today before the experiment , we first guess what : ? If you
let the nails with a core through the power , how would " immediately
active in the students up,
raised their hands , some students said: " let battery short ! " the
teacher said with a smile : " ? ah , yes, but it definitely will happen
," another student replied: . " nails will live hand feels will be a little numb . " But when the teacher made " NO " gesture when the students sat down with disappointment . I do not know what will happen , the teacher does not know what is snake oil medicine .
"Well
, let's do an experiment to answer it ! " Then , all of a sudden the
teacher's podium "change" ( a "change ", which highlights an interesting
experiment . ) Out of the experimental equipment : a battery box, a
battery , two long wires and critical of the trial - the nails . Teacher first wire wound on nails, and then open the switch.
We stared wait one miracle . Miracles really there ! Common
nails have a magnetic moment , "snapped ! Snapped ! Popping ! " Three
paperclip was sucked up , we were surprised to see the magic of the
"solenoid ." But many of the " question mark" has cropped : How electromagnets work ? It is what purpose ? What is it constructed ? ...... ( A series of questions , not only to seize the reader's heart , raises below. )
We
seem to see the teacher 's mind , then smiled and explained : "The
electromagnet is a device that generates a magnetic force after power at
the core of its power to match the external winding wire winding ,
magnetic, also called electromagnets. like
our maglev train is through the principle of electromagnet manufactured
" ( unlock secrets , there are examples of both , so that the reader
can easily understand the principle of the electromagnet . ) , I think:
this is not only an interesting experiment to do , but also to
understand the truth is really best of both worlds ah !
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