$I.\quad$ Am Punkt $t_1$

 $U_{A}(t_1) \ \ = -\quad { 1 \over {\tau} } \quad \ \cdot \int_{t_0}^{t_1} \quad U_E \ dt \ + \ U_{A}(t_0)$ $\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\quad$ $\qquad\qquad$
 $U_{A}(t_1) \ \ = -{ 1 \over {5 k\Omega \cdot 1 \mu F} }\cdot\int_{0}^{10ms} 1V \ dt + 0V$ $\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\quad$ $\qquad\qquad$
 $U_{A}(t_1) \ \ = - \quad { 1 \over {5 ms} } \quad \cdot 1V \ \cdot \int_{0}^{10ms} \ dt\quad\quad$ $\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\quad$ $\qquad\qquad$
 $U_{A}(t_1) \ \ = - \quad { 1 \over {5 ms} } \quad \cdot 1V \ \cdot [t]_{0}^{10ms} = \quad -2V$ $\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\quad$ $\qquad\qquad$

$I.\quad$ Am Punkt $t_2$

 $U_{A}(t_1) \ \ = -\quad { 1 \over {\tau} } \quad \ \cdot \int_{t_0}^{t_1} U_E \ dt \ + \ U_{A}(t_0)$ $\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\quad$ $\qquad\qquad$
 $U_{A}(t_1) \ \ = -{ 1 \over {5 ms} } \quad \cdot (-1V) \ \cdot [t]_{10ms}^{20ms} + 2V = 0V$ $\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\quad$ $\qquad\qquad$

$I.\quad$ Am Punkt $t_3$

 $U_{A}(t_1) \ \ = -\quad { 1 \over {\tau} } \quad \ \cdot \int_{t_0}^{t_1} U_E \ dt \ + \ U_{A}(t_0)$ $\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\quad$ $\qquad\qquad$
 $U_{A}(t_1) \ \ = -{ 1 \over {5 ms} } \quad \cdot (-2V) \ \cdot [t]_{10ms}^{20ms} + 0V = -2V$ $\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\qquad\quad$ $\qquad\qquad$