ELECTRIC MOMENTUM. INDUCTANCE. 159 



113. A certain spool wound full of wire o. I centimeter in diam- 

 eter has an inductance of 0.08 henry. The same spool is wound 

 full of wire 0.32 centimeter in diameter. What is its inductance ? 

 Ans. 0.000762 henry. 



114. A spool 5 times as large as the spool mentioned in prob- 

 lem 1 1 6 but similar in shape, is wound with wire 6 millimeters in 

 diameter. What is its inductance ? Ans. 0.193 henry. 



