DIRECT-CURRENT DYNAMOS AND MOTORS. 35 
what will be the consequence of employing too small a 
number of turns of this wire? 
32%. Give formula for the permissible power loss corresponding 
to a given temperature increase of a magnet. 
328. What is the formula for the shunt current which causes a 
prescribed rise of temperature in a magnet of given 
size? 
3229. Express the maximum shunt current in case the tem pera- 
ture increase is limited to 50° C. 
330. From Table 2%, Instruction Book, find the approximate 
winding height of a cylindrical magnet, 9” in diameter, 
when used for a multipolar machine. 
331. What is the approximate depth of winding on a 24” by 
43” rectangular core for a bipolar machine? 
332. Compute the approximate length of the mean turn on a 
bipolar magnet 20 inches in diameter. 
3335. Find the approximate average length of turn on a 6}" by 
| 17” multipolar magnet. 
334. Determine the cooling surface of a bipolar magnet, 12’\in 
diameter and 18” long, taking the external surface and 
both end surfaces of the coil. 
335. Figure the cooling surface of a multipolar rectangular 
magnet, 44’ by 12” in cross-section, 6” long, including 
but one of its end surfaces into the cooling surface. 
336. Required the cooling surface of an oval magnet whose 
cross-section consists of a 4-inch square enclosed between 
two semi-circles, and whose length is 8 inches; the 
magnet is intended for a bipolar machine and only one 
of the end surfaces is to be taken into account for cool- 
ing. 
33%. The total number of ampere-turns required for normal 
load being given, how is the number of series ampere- 
turns of a compound dynamo found? 
