Exercises
1. Does the spark of an induction coil occur at "make" or at "break?" Why?
2. What must be the relative number of turns upon the primary and secondary coils of a transformer if it receives current at 220 volts and delivers current at 110? Also show by diagram.
3. Would the transformer work upon a direct current? Why?
4. Explain why the interrupter is a necessary part of the induction coil and not of the transformer.
5. If a building used eighty 110-volt incandescent lamps, what would be necessary to light them if they were joined in series? Why would this not be practical?
6. If a 16-candle-power lamp requires 0.5 ampere upon a 110-volt circuit what current and voltage will be needed to operate 12 such lamps in parallel?
7. What will it cost to run these lamps 4 hours a night for 30 days at 10 cents per kilowatt hour?
8. If a mercury arc rectifier uses 5 amperes of current at 110 volts alternating current to produce 5 amperes of direct current at 70 volts, what is the efficiency of the rectifier?
9. Compute the heat produced in a 40 watt tungsten lamp in 1 minute.