69. Two particles $\alpha$ and $\beta$ enter a uniform magnetic field in the same direction and with the same speed. Under the influence of the field, which particle follows a path with a smaller radius of curvature, and what is the reason?
[(1)] $\beta$, its mass is smaller.
[(2)] $\beta$, its electric charge is greater.
[(3)] $\alpha$, it acquires greater speed.
[(4)] $\alpha$, a greater force acts on it.
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\textbf{69.} Two particles $\alpha$ and $\beta$ enter a uniform magnetic field in the same direction and with the same speed. Under the influence of the field, which particle follows a path with a smaller radius of curvature, and what is the reason?
\begin{itemize}
\item[(1)] $\beta$, its mass is smaller.
\item[(2)] $\beta$, its electric charge is greater.
\item[(3)] $\alpha$, it acquires greater speed.
\item[(4)] $\alpha$, a greater force acts on it.
\end{itemize}
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