# Why derive electric field produced by a rod?

1. Sep 15, 2010

### damosuz

Is there a practical utility to derive the electric field produced by a charged rod (and the 1/r dependence at great distance)? I know it can be useful to derive the electric field produced by a large plate since you can then show that the field between close parallel plates that are oppositely charged is uniform, which is useful info for experimenters.

2. Sep 15, 2010

### Bob S

What is the electric field 50 feet below a 700 kV interstate high-voltage power line (= long rod)? (ac power lines are actually 3 phase).

What is the minimum diameter of a high voltage power line to prevent corona?

Bob S

3. Sep 15, 2010

### damosuz

I meant the electric field produced by a static charge on a rod, not the intensity of the electric field in the radiation produced by the ac current in a wire (which is 1/r dependent too).

4. Sep 15, 2010

### Bob S

At 50 or 60 Hz, the radiation (like from antenna) is minimal, so the power line problem becomes quasi-electrostatic. The high-tension power line hazard is the quasi-electrostatic field, not a radiation field.

Bob S

5. Sep 16, 2010

### damosuz

Thank you for your help. Do you have any reference about this?

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