Constants oj a Rectangular Galvanometer. 



801 



or 



d^= 



d<f> 



p cos <f> + y/a 2 —p 2 sin 2 </> 



An integration sufficiently exact for our purpose may be 

 obtained by neglecting the quantity under the radical sign. 

 Hence 



Jo 1 



d<j> 



p COS (£> 



= -log (tan (f) X + sec <£ a ) 



■ /2v cvc — a + a\ 



log J - I, 



°\ 2c — a / 



(c — aJ^/2 

 substituting the values of tan (/>! and sec (j> l from fig. 10. 



Fig. 10. 



Putting a = kc, and neglecting squares of k, 



?= 



7> lo g 



c(l-k)V2 



1 2-ife J 



1} 



(l-ife)cV2 



