Effect of Negative Charge on the Radius of a Soap Bubble

Introduction
Soap bubbles are thin films of soapy water that trap air inside them. They have a spherical shape due to the surface tension of the water molecules. When a soap bubble is given a negative charge, it alters the surface tension of the bubble. This change in surface tension has an effect on the radius of the bubble.

The Effect of Negative Charge on the Surface Tension of a Soap Bubble
The surface tension of a soap bubble is the force that holds the bubble together. When a soap bubble is given a negative charge, it affects the electrostatic forces between the water molecules. The negative charge repels the negatively charged water molecules, leading to a decrease in the surface tension of the bubble.

The Effect of Decreased Surface Tension on the Radius of a Soap Bubble
The surface tension of a soap bubble is directly proportional to its radius. When the surface tension decreases, the radius of the bubble increases. This is because the force holding the bubble together is weakened, allowing the air trapped inside the bubble to expand further and increase the radius of the bubble.

The Answer
Therefore, the radius of a soap bubble increases when it is given a negative charge. This effect is due to the decrease in surface tension caused by the negative charge. The negative charge weakens the force holding the bubble together, leading to an increase in the radius of the bubble.