Consider a system of charges

*q*1,*q*2, ...*, q**n*with position vectors**r**1,**r**2, ...,**r***n*relative to some origin O. Like the electric field at a point in space due to a single charge, electric field at a point in space due to the system of charges is defined to be the force experienced by a unit test charge placed at that point, without disturbing the original positions of charges*q*1,*q*2, ...,*q**n*.
We can use Coulomb’s law and
the superposition principle to determine this field at a point P denoted by
position vector

**r**.
Electric field

**E**1 at**r**due to*q*1 at**r**1 is given by
where 1P ˆ

**r**is a unit vector in the direction from*q*1 to P, and*r*1P is the distance between*q*1 and P. In the same manner, electric field**E**2 at**r**due to*q*2 at**r**2 is**r**is a unit vector in the direction from

*q*2 to P and

*r*2P is the distance between

*q*

*2*and P. Similar

expressions hold good for
fields

**E**3,**E**4, ...,**E***n*due to charges*q*3,*q*4, ...,*q**n*.By the superposition principle, the electric field**E**at**r**due to the system of charges is (as shown in Fig)**E**is a vector quantity that varies from one point to another point in space and is determined from the positions of the source charges.

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**Some of these questions which may be asked in your Board Examination 2012-2013**

**Q1: What is a charge?**

Q2: What is the SI unit of Charge?

Q3: What is charge on a neutron?

Q4: what is the change on an electron?

Q5: Explain what is an fundamental electronic charge?

Q6: what is main cause of charging?

Q7: Electrostatic forces are much stronger than gravitational forces. Give one example.

Q8: What is the value of charge on an electron? is a charge less than this value possible?

Q9: What is charge on a photon?

**Answer these questions in comment box and help your friends**

Thanks

ReplyDeleteS I unit of charge is Coulomb

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