Power, voltage and capacitor problem

1) A tungsten filament has a resistance of 3 OMP at 20 degrees. When connected to a 100V power supply a current of 6.0A passes through a filament. If the filament is connected to the same power supply when it is at 2000 degrees, what will be the current through the filament and its power loss? 2) A battery whose emf is 12V is used to operate a device that draws 6.5A. When the device is operating the battery voltage is checked and found to be 8.2V. What will be the battery voltage be when it is connected to a device drawing 4.4A? 3) An electric car is designed to run off a bank of 12V batteries with total energy storage 2*10^7 j. If the electric motor draws 800W in mov... click for more

Working with the variation of resistance in regards to temperature.

(a) A 5 m length of copper wire at 20°C has a radius of 0.25mm. If a potential difference of 10V is applied across the length of the wire, determine the current in the wire. (b) If the wire is heated to 50.0°C and the 10 V potential difference is maintained, what is the resulting current in the wire?

Capacitor question

In the following circuit, what is the current through R1 at T=1 second after the switch is closed? How long does it take the capacitor to be 95% fully charged? See attached

Resistance problems

1. Find the current in each resistor in attachment #1 which is #27 on the page and it is circled. I need to see how you get your answer though. 2.Find a). the equivalent resistance of the circuit in the second Attachment or #47 on page and it is circle as well, b).each current in the circuit, c). the potential difference across each resistor, and d). the power dissipated by each resistor. 3. The student engineer of a compus radio station wishes to verify the effectiveness of the lightning rod on the antenna mast, this is attachment #3 and it says Figure P18.55. The unknown resistance Rx is between points c and e. Point e is a "true ground" but is inaccessible for direct measurement ... click for more

Magnetism problems

1.at a certain location, Earth has a magnetic field of 0.6*10^4T pointing 75degrees below the horixontal in a north-south plane. A 10m long straight wire carries a 15Acurrent. A)if the current is directed horizontally toward the east, what are the magnitude and direction of the magnetic force on the wire? B)What are the magnitude and direction of the force if the current is directed vertically upward? 2.In 1962, measurements of the magnetic field of a large tornado were made at the Geophysical Observatory in Tulsa, Ok. If the tornado's field was B=1.5*10^-8T pointing north when the tornado was 9.00km east of the observatory, what current was carried up or down the funnel of the tornado... click for more