Two point charges q and - q separated by a distance 2x constitute a electric dipole. Then, direction of the axis of this dipole is:

Options

A. from positive charge to negative charge
B. perpendicular to the line joining the two charges drawn at the centre and pointing in upward direction
C. perpendicular to the line joining the two charges drawn at the centre and pointing in downward direction
D. from negative charge to positive charge

Explanation

To solve the question regarding the direction of the axis of an electric dipole formed by two point charges \( q \) and \( -q \) separated by a distance \( 2x \), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Electric Dipole**:
An electric dipole consists of two equal and opposite charges separated by a certain distance. In this case, we have a positive charge \( q \) and a negative charge \( -q \) separated by a distance of \( 2x \).

2. **Identifying the Charges**:
Let's denote the positive charge \( q \) located at point A and the negative charge \( -q \) located at point B. The distance between these two charges is \( 2x \).

3. **Defining the Dipole Moment**:
The dipole moment \( \vec{p} \) is defined as:
\[ \vec{p} = q \cdot \vec{d} \]
where \( \vec{d} \) is the vector pointing from the negative charge to the positive charge. In this case, \( \vec{d} \) points from B to A.

4. **Direction of the Dipole Moment**:
According to the standard convention, the direction of the dipole moment is taken from the negative charge to the positive charge. Therefore, in our scenario, the direction of the dipole moment \( \vec{p} \) is from charge \( -q \) (point B) to charge \( q \) (point A).

5. **Conclusion**:
Since the dipole moment points from the negative charge to the positive charge, the direction of the axis of the dipole is from \( -q \) to \( q \).

### Final Answer:
The direction of the axis of the dipole is from the negative charge to the positive charge.