{"product_id":"geophysics-iii-geophysik-iii-part-iii-teil-iii-von-karl-rawer-hrsg","title":"Geophysics III\/Geophysik III","description":"Sect. 14. 297 for such slow variations the effect described under 2. above will be by far the most predominant. In fact, the equipment provides a record of the time derivative of the element in question. 6) Records of the time derivatives of magnetic elements can, however, be obtained in a more direct way by recording directly the electromotive force (e. m. f. ) induced in suitably disposed coils by the variations of the geomagnetic field 10, 11. When a coil with the total winding area F is placed with its axis in the direction of a geomagnetic force component the variation of magnetic induction B with time will produce an electromotive force 1 dB 1 dH e=- coveu,uuFdT=- 'oV~,uQf1oFdT (i). )) . !. . =_to-13~ d(B\/y) (1). )a) v em! d(tjs) in the coil. The e. mJ. may be amplified and recorded by means of an oscillograph or on a tape recorder. but more often the coil is used in connection with an ordinary galvanometer and the scale value of, for instance the dl1\/dt record, will then - in the same way as the scale value of the magnet variometer treated in Subsect. IX - be dependent on the damping factor IX and on TO\/T, where To and T are the oscillation periods for the undamped galvanometer and for the magnetic pulsation respectively. The amplitude recorded will be proportional to the amplification factor I, obtained from Eq. (1).\u003cdiv class=\"aw-variant-hidden-subtitle-div\" id=\"aw-variant-subtitle-9783642806414\"\u003e\u003ch3\u003ePart III\/Teil III\u003c\/h3\u003e\u003c\/div\u003e","brand":"Libri","offers":[{"title":"Softcover - 9783642806414","offer_id":39444735688797,"sku":"9783642806414","price":106.99,"currency_code":"EUR","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0940\/0622\/files\/155d7bb5-b81d-4503-9b44-85c9fe63e83c.jpg?v=1756009557","url":"https:\/\/shop.autorenwelt.de\/products\/geophysics-iii-geophysik-iii-part-iii-teil-iii-von-karl-rawer-hrsg","provider":"Autorenwelt Shop","version":"1.0","type":"link"}