678 Dr. J. A. Fleming on Magnetic Oscillators 



half of the oscillator with respect to the other, and V be 

 their maximum potential difference in volts before discharge, 

 then 9x 10 5 C V/ 300 = 3000 CV is the maximum value of 

 the charge in electrostatic units. 



Hence if I is the length of the oscillator in cms., we have 

 for the electric moment, 



= 3OOOC.V.Z (2) 



Let the current at the centre of the oscillator have a 

 maximum value A reckoned in amperes, and let a be the 

 root-mean-square or effective value in amperes as measured 

 by a hot-wire ammeter. 



Then, if the oscillations are sinoidal in form, undamped or 

 persistent, and of frequency N, we have 



A=2ttNCV/10 6 , (3) 



«=4 '■ w 



Hence the energy E radiated per period in ergs is 

 given by 



E=4«*10»5£, ( 5 ) 



and the power W in watts by 



W = 40tt 2 ^A 2 (6) 



Remembering that 7r 2 = 9'87 and N\ = 3 X 10 10 , we can write 

 the above formulae in the convenient form 



E = 0'2632^a 2 , (7) 



W = 789-6 ~a 2 (8) 



The value of the ratio I / X can be determined experiment- 

 ally for any oscillator. For a simple linear oscillation it 

 approximates in value to 0*4. Hence for such an oscillator 

 radiating undamped waves, the power radiated in watts is 

 given by the expression W=126« 2 . Thus, for instance, if 

 the effective value of the current at the centre of the 

 oscillator is 2 amperes, the radiation will be half a kilowatt. 

 If we then consider the case of a perfectly closed oscillation 

 circuit having an area S and traversed by undamped or 

 persistent oscillations which have a maximum value A and 

 R.M.S. value a reckoned in amperes, it can be shown that 



