Two identical conducting spheres with same potential in a uniform electric field

•A new method is put forward to ensure the validity of image method.•The repulsive interaction is measured from experiment firstly.•Electric interaction in shorted case is very different with that in not shorted case.

Interaction, polarization, and charges or electric field distribution of conducting spheres in applied electric field are in many fields including electrorheological fluids, electrophoresis, and electrical engineering. A system with two equipotential conducting spheres in an applied uniform electric field is analyzed by image method. A new method is put forward to calculate the image charges distribution when using image method, which ensures the validity of image method to analyze equipotential cases. An apparatus is constructed to measure the force experimentally as well. Results show that the distribution of electric field and electric interaction are different with the case not equipotential.