# Lines of electric field

1. Apr 29, 2010

### Misr

Hello
The electric field lines comes out from a positive charge towards infinity (towards the equal negative charge)..
Oops !! confused again bout infinity
Why is this true?
Thanks

2. Apr 29, 2010

### LostConjugate

It is true because it is measured. All of classical physics takes the electric field as a given based on measurements. Quantum Field Theory attempts to explain the mechanism.

3. May 2, 2010

### Misr

It is not that sophisticated its a simple question
What is the definition of infinity in this case??
also why does the +ve charge move in the direction of electric field while -ve one moves opposite to the direction of electric field?

4. May 2, 2010

### Born2bwire

*shrug* Infinity is the limit of the volume of space increasing to infinite volume. You can do this in a variety of ways. Take a sphere and take the limit of the sphere's radius to infinity for example. For this problem it shouldn't matter how you do it as the limiting cases should be the same.

The electric field is a field that applies a force on a test charge, specifically it is qE (E is a vector here) as given by the Lorentz force. Since positive and negative charges have opposite signs, the direction of the force is opposite.