\textbf{166-} A ball is placed at the midpoint between a spherical lamp and a wall, and the diameter of the ball equals the diameter of the lamp. The width of the shadow formed by the ball on the wall is how many times the diameter of the ball?
\hfill (1) $1$ \hfill (2) $2$ \hfill (3) $3$ \hfill (4) $4$