Weak and electromagnetic interactions have actually been unified as different aspects of a single force called the "electro-weak force." Historically, the weak force was seen to underlie certain kinds of radioactive decay at a sub-atomic scale. Electromagnetic interactions, on the other hand, affect matter at the atomic scale. However, it has been shown that at high enough temperatures/energies (i.e. energies exceeding the "unification energy"), the two "types" of interactions actually merge into one. I hope this helps.