I have some electricity questions!?

1.In the U.S., the electrical system runs on current that reverses 60 times per second which is referred to as ____________________ current.
 
2.Materials through which charge flows easily are called ____________________.
 
3. Tungsten is used in light bulb filaments because it glows when hot, rather than melting. The thin tungsten filament gets very hot in a circuit because it has high ____________________.
 8. A miniature light bulb with a resistance of 3 ohms is connected to a 6-volt source. How much current will flow through the bulb?
 
9. In many homes, 75-watt light bulbs are common. If the bulb is connected to a 120-volt source, what is the resistance to the flow of charge in the bulb?
 
The label on a radio identifies the radio's power consumption to be 4.0 watts when operating at 120 volts. Use this information to answer the following questions:
 
10. The rate at which current flows through an appliance is often referred to as its "draw." How much current does this radio draw?
 
11. The power company charges 15 cents per kilowatt-hour of energy. How much would it cost to run this radio for 30 minutes?
 
12. In many homes, 75-watt incandescent light bulbs are common. In one home there are 10 lights, and each light is on 90 hours per month. If the power company charges 15 cents per kilowatt-hour of energy, how much money will be saved each month if all the incandescent bulbs are replaced with 25-watt fluorescent bulbs?
 
13. Measured in kilowatt-hours, how much energy does a 4500-watt water heater element use in 2 hours?
 
PLEASE HELP ME

1) Alternating
2) Conductors
3) Resistance
V= IR, therefore I = V/R = 6/3 = 2 A
11) 4.0 W = 0.004 kW. Take it to be 0.004 kWh, it will cost 0.004kWh x 1/2h x 15 cents = 0.03 cents

1. alternating current
2. conductor
3. resistance
8.v=i*r, 6v=i*3 ohm, i=2 amps
9. p=i*v, 75 W = i*120v, i=75/120 amps, .625 amps,  v/i=r, 120/.625=r, r=191.693 ohms
10. to answer this question you must understand what current is,  current is exactly what he describes as "draw" so...  p=i*v, 4 W=i*120v, i=.0333 amps
11. a watt is a measure of energy/time.  so a kilowatt-hour translates to (energy/time)*time which simplifies to energy.  the units of time dont matter (you just must know that 30 min is 1/2 of an hour. which means if a one kilowatt source ran for 30 min [$0.075] it would cost half as much as if it ran for a full hour [$0.15).  this being said  1Kilowatt=1000watts so 4W=.004KW, .004KW*$.075= $.0003
12. .075W*10 bulbs*90hr=67.5 KW*hr, .025W*10 bulbs*90hr=22.5 KW*hr, 67.5-22.5=45KW*hr, 45KW*hr* $0.15=$6.75
13. 4500W=4.5KW, 4.5KW*2hr= 9KW*hr