生成视频---**Textual Information:** **Question Stem:** 如图所示，A、B、C三点的连线构成一个等腰直角三角形，∠A是直角。在B点放置一个电荷量为+Q的点电荷，测得A点的电场强度大小为E。若保留B点的电荷，在C点放置一个电荷量为-Q的点电荷，则A点的电场强度大小等于（ ） **Options:** A. 0 B. E C. $\sqrt{2}E$ D. $2E$ **Chart/Diagram Description:** * **Type:** Geometric figure (Triangle). * **Main Elements:** * **Points:** Three points labeled A, B, and C, forming the vertices of a triangle. Point A is at the top, B is on the lower left, and C is on the lower right. * **Lines:** Three dashed lines connecting A to B, A to C, and B to C, forming the sides of the triangle ABC. * **Shapes:** A triangle ABC. * **Angles:** A right angle symbol is shown at vertex A, indicating that ∠A is a right angle. * **Labels and Annotations:** The vertices are labeled A, B, and C. The right angle at A is indicated. * **Relative Position and Direction:** A is above B and C. B is to the left of C. The figure represents a triangle with vertices A, B, and C, where the angle at A is 90 degrees. The problem states it is an isosceles right-angled triangle with ∠A as the right angle, implying the sides AB and AC are equal in length. The line BC is the hypotenuse.