Group V 



13. a) (2) Describe a leaf electroscope. 



b) (3) Describe how tlie electroscope may be charged by the method of 



induction. 



c) (3) Explain tlie various steps of the process. 



d) (2) Explain how tlie electroscope is used to tell that a body is positively ^ 



charged. ' 



14. A 40-watt incandescent lamp is connected to a 100-volt circuit: 

 c) (3) What current passes through the lamp ? 



b) (2) If three such lamps are connected in parallel in the above circuit, what 



current passes through each lamp ? 



c) (2) If the three lamps are connected in series, what current passes through 



each lamp ? 



d) (3) If the three lamps are connected in parallel and used 10 hours each 



day for 4 weeks, and the cost is 8 cents per kilowatt-hour, what will 

 be the total cost ? 



15. a) (1) Whose name is associated with the discovery of induced currents? 



b) (2) What is Lenz's Law for the direction of induced currents ? 



c) (2) Name two machines or pieces of apparatus that depend upon induc- 



tion for their usefulness. 



d) (!) In what other way are currents of electricity commonly produced ? 



e) (1) Which was discovered first ? 



/) (1) Which is the more important today ? 



g) (2) Give some reasons for your last answer. ;|| 



1-4 



