The improper integral is of the form:
\[
I(p) = \int_1^\infty \frac{dx}{x^p}
\]
To determine the value of \( p \) for which this integral converges, we first evaluate the integral for different values of \( p \). The general formula for this type of integral is:
\[
\int_1^\infty x^{-p} dx = \frac{1}{1-p} \quad \text{for} \quad p>1
\]
For \( p \leq 1 \), the integral does not converge because the integral will diverge as \( x \to \infty \).
Therefore, the integral converges for \( p>1 \).
Thus, the correct answer is 1. \( p>1 \).