M/r /: If. \'. \ri\a CURRENT AND VOLTAGE 



9 



alternating-current umpcre is that current which, flowing 

 '/ ohnu'c resistance, mil produce heat at the same rate 



Assume that a resistance unit is immersed in a calorimeter 



and that when a direct -current ampere is sent through this 

 tance the temi>erature of the water is raised 20 in 10 niin. 

 Iternatinir-current ampere, if sent through this same resis- 

 tance unit, will raise the temperature of t lie water by the same 

 amount in the same time, other conditions such as radiation, etc., 

 being the same. That is, both currents produce heat at the 

 same rate. 



\ 



i 



Time 



() CO 



.. 7. Maximum and rfiVrti\<- v:ilu- of sinr-wuvc altcrnatiim current 



The heating elTecl varies as the .sv/w/rr of the current ( - 



. the value in amperes of the wave of current in Kiu. 7 



ie based ujxni i; dues. Fiirure 7 (/*) shows 



irrent \\ plotted, together with its scjuared 



values. That i-. -ach ordinal*' of the "/" wave is stpiaivd and 



lotted t. inwn. The maximum 



of this new wave will be 2.0 (- 1.1 11;' since the maximum 



valu<- of the original iMirreni wavr i- 1.111 or \ 2. The squared 



entirely above the ^ ause the s.juare of 



bwioe that of th. 



symmetry at a distance 

 lie zero axis, as shown in Fig. 7 (6). The average 



