1 / 7

Electric Power

Electric Power. Electric Power. Recall from 1 st Semester that power is defined as the rate at which work is done. Power = Work/Time The units of Power are Watts 1 Watt = 1 Joule / 1 Second The Power it takes to move a Charge across a Voltage in a certain time is:

aric
Download Presentation

Electric Power

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Electric Power

  2. Electric Power • Recall from 1st Semester that power is defined as the rate at which work is done. • Power = Work/Time • The units of Power are Watts • 1 Watt = 1 Joule / 1 Second • The Power it takes to move a Charge across a Voltage in a certain time is: • P = (V∙q)/t = V∙(q/t) = I∙V • Recall Ohm’s Law: • I = V/R or V = I·R • Combine with P = I·V: • P = V2/R • P = I2·R • See next page for graphic organizer of equations relating P, I, V, and R

  3. Example Problem #1 • The iPod Nano uses 5.0 Watts of power. • Determine how much energy it consumes during 10 hours of listening time. • Determine the resistance of the IPod if it uses a 5.2 Volt battery. • What quantity of charge passes through the IPod battery during this 10-hr time period?

  4. Example Problem #2 • Calculate the energy used and current drawn by a: • 200 W window fan when plugged into a 110 V outlet and left on for an 8 hour time period. • 3400 W air conditioner that is wired to a 220 V circuit and left on for an 8 hour time period.

  5. The Cost of Electricity Cost per unit of Electrical Energy Electrical Energy Used Total Cost = x ($) (kWh) ($ per kW·h) • The electric company charges you for the amount of ENERGY they provide to you. • Energy provided is “Work” • Measured in strange unit: “KiloWatt-Hours” • $0.0776 per kWh in NoVA • Household Electric Sockets operate at 120 V in the U.S. • Heavy equipment outlets (welders, clothes dryers, ovens, etc) operate at 240 V • Other countries operate at different voltages • Cars operate at 12 V

  6. Example Problem #3 • A 2000 W hand dryer in a public bathroom at a zoo runs for 30 seconds per cycle. • At a cost of 13 cents per kW•hr, determine the cost of running the dryer 200 times in a day. • What is the annual cost of the hand dryer assuming it is used on average 200 times per day? • Calculate the resistance and the current for the hand dryer if it is connected to a 220-V circuit.

More Related