The Goal of This Sheet Is to Give You a Record of Your Reading

Electric Current

The goal of this sheet is to give you a record of your reading.

Write the answers in your own words.

List the three situations when an electric current is produced.Draw a diagram showing the movement of charge for each one.

Write the definition of Current. Draw a diagram of the charge crossing a surface area.

The diagram shows a current-carrying metal wire. Using a black pen or pencil, indicate the direction of the charge carriers. Using a different colour pen, indicate the direction of the E field.

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/ A light-bulb is connected to a battery as shown, such that the bulb lights up. The diameter of the wires are constant. Draw the direction of the E field just inside the wires at the points indicated. Rank the magnitude of the E field at the points, from smallest to biggest.

In your own words, describe what is meant by the term drift velocity? Write the equation relating the current to the drift velocity. Make sure to define each term in the equation and draw a diagram if necessary.

Write the relationship between Resistance and resistivity:______

Write the mathematical expression of Ohm’s Law:______

Write the mathematical expression of the power dissipated in a resistor:______

/ A wire is made of two different segments with different radii, but made out of the same metal, and same length. The current in segment 1 is I1. The resistance across 1 is R1; the potential is V1; the power P1.
Is I2 greater than/smaller than/ equal to I1? (circle answer)
Explain:
Is R2 greater than/smaller than/ equal to R1?
Explain:
Is V2 greater than/smaller than/ equal to V1?
Explain:
Is P2 greater than/smaller than/ equal to P1?(
Explain:

Example Problem:

In the laboratory, solid copper rods are used to carry large currents. Current flows from a section with a diameter of 4.00cm to a section with a diameter of 1.00cm. You measure that the potential difference across a 2.00m segment of the bigger section of the rod is 13.4mV.

a)What is the potential difference across the 1.00m segment of the smaller section of the rod?

b)Compare the speed of the electrons in the smaller and in the bigger section of the rod.

Resistivity of copper =copper=1.69×10-8 m and the number of charge carriers per unit volume for copper is ncopper=8.49×1028electrons/m3.

The solution is found in this videoExercise Solution.

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