Please Help!! Mirrors/lenses
I have been working on a Physics assignment for a long time now, and I can't seem to figure out three questions. It's due tonight, so any help would be greatly appreciated!!
Here they are:
1. A dentist uses a small mirror of radius 36 mm to locate a cavity in...
Transformer efficiency/primary current (help!!)
Real transformers are not 100% efficient. That is, the efficiency, in percent, is represented by e = (100%) Ps/Pp. A step-down transformer has an efficiency of 92.5% is used to obtain 23.0 V from the 125 V household voltage. The current in the...
Re: **Transistor radio/kWh problem**
So if one kWh = 3.6E6 J, and the total energy is 518,400 J..
(3.6E6)/(518400) = 6.9444
--> (6.9444)(6) = 41.666
Is 41.666 cents the answer? I only have two more tries left and I don't want to get it wrong. I'm not sure if those are the correct unit...
**Transistor radio/kWh problem**
A transistor radio operates by means of a 10.0 V battery that supplies it with a 48 mA current.
(a) If the cost of the battery is $0.55 and it lasts for 300 h, what is the cost per kWh to operate the radio in this manner?