What is Wattage: Definition and 67 Discussions

Electric power is the rate, per unit time, at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt, one joule per second.
Electric power is usually produced by electric generators, but can also be supplied by sources such as electric batteries. It is usually supplied to businesses and homes (as domestic mains electricity) by the electric power industry through an electric power grid.
Electric power can be delivered over long distances by transmission lines and used for applications such as motion, light or heat with high efficiency.

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  1. T

    Understanding Voltage, Amperage, and Wattage for DC Motors at Low RPMs

    Hello All- COuld someone please give me a primer on DC as it pertains to voltage, amperage and wattage. Specifically, if I have a motor that i need to run at very low RPM (50 -150), how does the motor compare across a 12v system vs. a 24, 48 or even 60v system. Do 60v systems run more...
  2. J

    HW: What is energy used? What is wattage?

    Cutnell Physics 7th Ed pg 600 # 39 Homework Statement A camera flash has a capacitor. Capacitor has a rating of: 850uF The potential difference between the places is: 280V a) Determine Energy used to produce flash. b)If flash lasts 3.9E-9 S, what is the power or wattage of the...
  3. A

    Calculating KWH Generated by a Water Turbine?

    I'm attempting to calculate the amount of power (in KWH) produced by a water turbine based on x litres of water falling x metres vertically through a tube of x cm diameter So far I've managed the following: H = height (distance fallen) (m) Time = Secs R = Radius of the pipe (m) Velocity...
  4. I

    Connecting AC Power Lines: Understanding Wattage & Current

    What is the proper way to connect several ac power lines into one line. So let's say if you had 20 lines and each had a 10 volts and 1 amp of power so 10 watts AC. When connecting them into one line would you have 200 watts. Also with it being alternating what would happen when the current is in...
  5. J

    How Do You Calculate the Variable Resistance for Optimal Battery Charging?

    Homework Statement http://img2.freeimagehosting.net/uploads/bf073a5eb1.png http://img2.freeimagehosting.net/uploads/bf073a5eb1.png Determine the variable resistance R if the 25 Watts to be absorbed by the battery (0.035 ohm resistor and the 10.5 V element). Homework Equations V = IR P =...
  6. L

    How Much Power is Needed to Boil Water in a Coffee Mug?

    Homework Statement A 0.29 kg coffee mug is made from a material that has a specific heat capacity of 930 J/(kg·°C) and contains 0.23 kg of water. The cup and water are at 25°C. To make a cup of coffee, a small electric heater is immersed in the water and brings it to a boil in two minutes...
  7. M

    Understanding Wattage and Efficiency in Electrical Appliances: Explained

    In an ordinary electrical appliance they usually tell you the wattage of it on a tag. Does the wattage include all power loss throughout the whole circuit or does it only tell you the amount of power dissipated at the main components. For example say I have a flashlight. Would the wattage on the...
  8. B

    Figuring Out Wattage of My Laptop - Mark's Query

    hi, the attached image is from the back of my laptop. i'm trying to figure out how much watts it consumes per hour. i know that power is current multiplied by volts. so its 90.09 watts = 4.62 amps * 19.5 volts. is this the watts per hour? thanks, mark
  9. R

    Calculating Wattage of a Light Bulb in a Soot-Covered Room

    A light bulb is completely covered with a thin coat of black soot in a room maintained at 20 degree celsius. If the shell has an equilibrium temperature of 100 degree celsius. What is the wattage of the bulb? I can't understand how to do it. I am a student of 9th standard.
  10. T

    Does Higher Resistance Mean Brighter Bulbs?

    Hi everyone ! First time to post! I am taking a distance course of a physics class now. I am bit confused about the resistance & wattage. In the circuit with the bulb, when there is a greater resistance with the bulb the more energy dissipate, therefore it shines brighter... I think...
  11. M

    Resistor Wattage: Higher or Lower for Low Resistance & Cooler?

    I am looking for a low resistance resistor to put in my circuit to lower the current slightly. My circuit is/will be running off a 12 power supply and normally will draw somewhere between 11 and 13 amps under normal operation. I would like to add in an additional maybe .5 to 1 ohm resistor so...
  12. D

    Increase Voltage without Increasing Wattage?

    1. Is it possible to increase voltage without increasing wattage? 2. If 1. is yes, then is it more common that when voltage is increased wattage increases aswell? Thanks
  13. M

    Wattage: Understanding Output for Wireless Devices

    microwave wattage... How is output wattage determined for wireless devices? For example, microwave ovens emit sound waves at similar fequency to wireless devices, yet they cook food. I know my cell phone is at 2.5 ghz, but the wattage output is so low that it supposedly does not affect me. My...
  14. M

    Calculating the Wattage Usage of a 60-Watt Light Bulb in Three Hours

    How may watts does a 60-watt light bulb use in three hours? 60*3=180watts?
  15. P

    Calculate Current for 100W Lamp in 110V & 220V Circuits

    A 100w lamp in a 110 v circuit produce how much current? Also, the same 100w lamp in a 220 v circuit produces how much current? How did you get your answers?
  16. marcus

    The Hawking wattage of a black hole

    Assume the surface area of the event horizon of an ordinary black hole is 1050, ordinary meaning uncharged and nonrotating. The hole glows with Hawking radiation----what is the radiant power? I gave the event horizon area in natural units but it's easy to convert to square meters if you...
  17. dav2008

    What is the Wattage of a Microwave Oven?

    Just a quick question on microwave ovens if anyone knows it... If an oven is said to be 1000 Watts, does that mean it would use 1000 watts of electricity from the socket, or is that the rate at which food inside absorbs energy? If its the first, what would the rate of energy be that the...
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