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physicsphobic

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**urgently needed help on intro physics...**

This is my first time posting on here so I hope someone will answer my questions.

Here they are:

1. A scientist testing a material discovers that when a voltage of 10V is placed across a material a current of 10A flows. When a voltage of 20V is placed across it, however, a current of 15A flows through it. Does this material obey Ohm's law? Give reason for your answer.

2.a. How much power does a light bulb connected to a 120V outlet use if if draws 0.5A of current? My answer is: 120V *0.5A= 60W

b. One kilowatt-hour is a measure of energy which is equal to 3,600,000J. How many hours would you have to leave on the light bulb from part a in order to expend one kilowatt-hour of energy?

c. If one kilowatt-hour costs $.10, how long would you have to leave the light bulb from part a on in order to spend $1.00 on electricity?

3. The electric charge of an electron is -1.6x10^-19C. What is the force exerted between two electrons separated by one meter? (Be sure to note whether the force is attractive or repulsive).

Thanks for any help given to this newbie!

Joanne