Practical measurements in radio-activity / by W. Makower ... and H. Geiger.

  • Makower, W. (Walter), 1879-1945
Date:
1912
Catalogue details

Licence: Public Domain Mark

Credit: Practical measurements in radio-activity / by W. Makower ... and H. Geiger. Source: Wellcome Collection.

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    a charge induced on the insulated quadrants by the motion of the charged needle. This couple is known as the induc- tional electrostatic control, and will resist the deflection of the needle. The charge induced on the insulated quadrants will be proportional to V@, and therefore the difference of potential Ve O° where C is the total capacity of the electrometer and the ionisation vessel connected to it. Since this potential differ- ence is always small com- 7 set up between the quadrants will be proportional to pared with V, the resulting == couple may be written es =e © If q is the charge communi- ae a cated to the insulated quad- _| To Earth. rants through the ionisation ee vessel, the potential set up between the quadrants is q/C;, k.Vq and the corresponding deflecting couple on the needle is “a Hence, equating the deflecting and controlling couples, we have the relation | : k,V70 Vi k,O+kh,V20+ CO Te aE AR re (5) = kV q whence @= SITE ss Ge es (6) k,+hk,Vi+k, oO The expression may be written in the form CLS aN. Ma ET SR aa a) 2 ee poe i | But if there is no restoring couple other than the mechanical control, the deflection is given by Hence on account of the electrical control, the capacity of the electrometer appears to be altered from C to C Ph: A oe si “lh
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