Question

A simple electric dipole consists of a positive and negative charge of equal magnitude held very close to one another. The components of the electric field pointing away from a dipole has magnitude. where is the distance from the center of the dipole to the point in question, is a universal constant and p in the magnitude of the dipole moment vector, which specifics the strength and direction of the dipole. Here, denotes the angle between the dipole moment vector and d, the displacement vector (from the dipole to the point in question).

A student performs an experiment to determine if a mystery object is an electric dipole. (The mystery object is only a few millimeters long) Using a sophisticated instrument, the student measures the component of the electric field pointing away from the object, at various distances from the center of the object. By taking each measurement along an imaginary line emanating outward from the center of the mystery object, he ensures that stays the same throughout the experiments. Table 1 shows the electric field be found at various distances.

Consider the electric field produced by a dipole. If the dipole moment and the distance from the dipole are both doubled, while is kept the same, the electric field component pointing away from the dipole decreases by a factor of :

1. 2    
2. 4    
3. 8    
4. 16