Correct answer: \(\phi\)
Explanation:
Two events \( E_1 \) and \( E_2 \) are said to be mutually exclusive if they cannot occur at the same time. This means that the intersection of \( E_1 \) and \( E_2 \), denoted by \( E_1 \cap E_2 \), is the empty set, i.e., \( E_1 \cap E_2 = \emptyset \). Therefore, the value of \( E_1 \cap E_2 \) is \( \phi \), which represents the empty set.
Hence, \( E_1 \cap E_2 = \phi \).