Đáp án:
a) \({T_2} = 2,0002s\)
b) \(E = 20000V/m\)
Giải thích các bước giải:
a) Ta có:
\(\dfrac{{{T_1}}}{{{T_2}}} = \dfrac{{{\omega _2}}}{{{\omega _1}}} = \sqrt {\dfrac{{{l_1}}}{{{l_2}}}} = \sqrt {\dfrac{1}{{1 + \alpha t}}} \Rightarrow {T_2} = 2,0002s\)
b) Ta có:
\(\begin{array}{l}
{T_1} = {T_2}\\
\Rightarrow \dfrac{{{g_1}}}{{{l_1}}} = \dfrac{{{g_2}}}{{{l_2}}}\\
\Rightarrow \dfrac{g}{l} = \dfrac{{\sqrt {{g^2} + {{\left( {\dfrac{{qE}}{m}} \right)}^2}} }}{{l\left( {1 + \alpha t} \right)}}\\
\Rightarrow E = 20000V/m
\end{array}\)