An enormous amount of electricity is created at power-generating stations and sent across the country through wires that carry high voltages. Appliances,

 discussion- An enormous amount of electricity is created at power-generating stations and sent across the country through wires that carry high voltages. Appliances, power lines, airport and military radars, substations, transformers, computers, and other equipment that carries or uses electricity all generate electromagnetic fields.

Many questions have been raised about how electromagnetic fields affect our bodies. Do they pose a public health risk? Perform an Internet search to find information about the effects of electromagnetic fields on public health. Then, discuss the pros and cons of using equipment that produces an electromagnetic field.

Here is one authoritative source to get you started: electromagnetic fields and public health.

Double Helix Structure of DNA

This task connects the physics of electrostatics with molecular biology. Molecular biology is the study of the structure and function of the cell at the molecular level. DNA’s double helix structure consists of two strands held together by electrostatic forces. Do online research on electrostatics and molecular biology, and then answer the following questions. Here are two sources to start with:

• DNA  Deoxyribonucleic Acid (DNA) Fact Sheet 
• the structure and function of DNA   The Structure and Function of DNA – Molecular Biology of the Cell – NCBI Bookshelf 

Part A

What is DNA and what is its role in life? List DNA’s four nucleotide bases.

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Part B

Explain DNA’s structure, specifically noting the role electric fields and forces play in it.

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Electric Field of Dreams

In this activity, you will explore the relationship between the strength and direction of the electric field lines to the type of charge on a particle and its magnitude. You will also explore the interactions between two or more charged particles and observe their movement. To begin your activity, open the simulation: Electric Field of Dreams.  ‪‪Electric field of dreams‬ 1.0.0-dev.10‬ 

Directions:
At any time you may

• click the Reset All button to reset all the settings;
• click the Play/Pause button to pause or resume the motion; or
• pause the motion and then click the Step button to observe the motion step-by-step.

Part A

To begin, click the Add button to add one object to the system. Observe the electric field around this charged object. You may move the object around the field by dragging it with your cursor. While the arrows indicate the direction of the electric field around the charge, the length of the arrows indicates the field strength. Based on your observations of the field, what is the charge on this object? Give your reasoning.

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Part B

Set the charged object in motion by dragging it and releasing it. What do you observe about the behavior of the field lines in the vicinity of the object?

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Part C

Add another charged object to the electric field by clicking the Add button again. What is the charge of this new object? Give your reasoning. What do you observe about the behavior of both the objects as well as the field lines in the vicinity of both the objects?

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Part D

Click the Remove button to remove one of these objects, and then click the Properties button to set properties for the next object you will add. Just change the sign of the charge to (+), then click Done. Click Add to add this new object to the field. Now what do you observe about the behavior of the two objects and the field lines that surround them?

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Part E

With the two oppositely-charged objects still in the field, apply an external field to the system: In the External Field box, simply drag the dot until it becomes an electric field vector in some direction. Observe, describe, and explain the behavior of the two objects.

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Electric Field Hockey  ‪‪Electric field hockey‬ 1.0.0-dev.10‬ 

In this activity, you will again explore the relationship between an electric field and charged particles in the field, but this time you’ll have a gaming challenge. To begin, open Electric Field Hockey.

Directions:
On the control bar, make sure that the Puck is Positive and the Field boxes are checked. Also, make sure that the Practice option is selected.

Your aim is to score goals by manipulating the black puck (test charge) into the blue-colored bracket (goal) on the right. Think smart and place positive source charges (red) and negative source charges (blue) in such a way that the black puck moves into the goal.

Note that when you place a red, positive source charge in the hockey field, a red arrow appears on the black puck (test charge) showing the force the positive charge exerts on the puck. Similarly, when you place a blue, negative source charge in the hockey field, a blue arrow appears on the black puck (test charge) showing the force the negative charge exerts on the puck.

Part A

Place a red charge in the hockey field and click Start. In which direction do electric field lines point? In which direction does the black puck move? What conclusion do you draw from this movement?

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Part B

Click Reset and then click Clear. Now, place a blue charge in the hockey field and click Start. In which direction do electric field lines point? In which direction does the black puck move? What conclusion do you draw from this movement?

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Part C

Manipulate the mass of the puck by dragging the Mass bar to the right for increasing the mass and to the left for decreasing it. What changes do you see in the speed of the puck? Which principle works behind this change?

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Part D

In the same situation, what do you observe about the relationship between the speed of the black puck and its distance from the blue charge?

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Part E

You can make the puck travel in complex ways by placing a set of charges around on the field. So, here’s your game challenge: Arrange source charges around to propel the puck from its starting position into the goal. That’s pretty easy for a straight shot; you just put a negative charge behind the goal. But what if there are barriers in the way? That’s a real test of your physics understanding, including Newton’s laws of motion and electrostatic forces. Game’s on!

On the control bar, check the Trace, Field, and Anti-alias boxes. The game has three Difficulty levels. Start with Difficulty level one and arrange source charges to get the puck into the goal. Once you’ve made a score at any level, increase the Difficulty level. Take a screen capture of two of your most difficult goals and paste them here. At least one of these should be at Difficulty level 2 or 3.

(Note: On a Windows computer, you can use the key combination Alt-Print Screen to copy the currently-active window to your clipboard. When you capture an image of this simulation window, paste the image into an image-processing program such as Paint, and save the image as a file. Then use the Insert Image button to insert the file into the response area.)

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