# Rubber balloon in electric field

• phantom113
In summary, the question is asking for the charge inside a rubber balloon with evenly distributed charge on its surface when placed in a uniform electric field of 120 N/C. The correct approach involves using the principle of superposition and considering the polarizability of the balloon to relate the field to the dipole moment created and determine the charge on the inside.
phantom113

## Homework Statement

A rubber balloon has a charge q evenly distributed over its surface. It is put into a uniform electric field of 120 N/C. What is the charge inside the balloon?

## The Attempt at a Solution

I thought that E inside would be 120 since before it is put into the electric field, E inside is 0(true or not?). When it is put into the field you use the principle of superposition and they add to 120 N/C?

Any insight to this would be helpful. I handed it in this morning but I'd still like to know if I made correct assumptions.

phantom113 said:

## Homework Statement

A rubber balloon has a charge q evenly distributed over its surface. It is put into a uniform electric field of 120 N/C. What is the charge inside the balloon?

## The Attempt at a Solution

I thought that E inside would be 120 since before it is put into the electric field, E inside is 0(true or not?). When it is put into the field you use the principle of superposition and they add to 120 N/C?

Any insight to this would be helpful. I handed it in this morning but I'd still like to know if I made correct assumptions.
Assuming the balloon to approximate a spherical shell then I'd say you're right about the E-field, but you are missing a step, which is using the polarizability to relate the field to the dipole moment created and ultimately the charge on the inside.

I would like to clarify and expand on the concept of a rubber balloon in an electric field. Firstly, the assumption that the electric field inside the balloon is 0 before it is put into the field is not entirely accurate. The charge distribution on the surface of the balloon creates an electric field inside the balloon, although it may be much weaker compared to the surrounding electric field.

When the balloon is placed in the uniform electric field of 120 N/C, the electric field inside the balloon will not simply add up to 120 N/C. This is because the electric field inside the balloon is affected by the charge distribution on its surface. To determine the charge inside the balloon, one would need to consider the electric field inside the balloon and the electric field outside the balloon and solve for the electric potential using the principle of superposition.

In addition, the charge inside the balloon may not necessarily be evenly distributed like the charge on its surface. This can depend on factors such as the material of the balloon and the strength of the electric field. Therefore, it is not possible to accurately determine the charge inside the balloon without further information or experimentation.

Overall, the concept of a rubber balloon in an electric field is complex and requires a more thorough understanding of electric fields and charge distribution. It is important to note that the electric field inside the balloon is not simply the sum of the external electric field and the electric field created by the charge on its surface.

## 1. How does a rubber balloon behave in an electric field?

When a rubber balloon is placed in an electric field, it will experience a force due to the presence of opposite charges on either side of the balloon. This force will cause the balloon to deform and stretch in the direction of the electric field.

## 2. Why does a rubber balloon stick to walls when rubbed on hair?

When a rubber balloon is rubbed on hair, it becomes negatively charged due to the transfer of electrons from the hair to the balloon. This negative charge causes the balloon to be attracted to positively charged surfaces, such as walls, and stick to them.

## 3. What happens to a rubber balloon when placed in a strong electric field?

In a strong electric field, the force on the rubber balloon will be greater, causing it to stretch even further. If the electric field is strong enough, the balloon may even burst due to the tension in the rubber being exceeded.

## 4. Can a rubber balloon be used to demonstrate electric fields?

Yes, a rubber balloon can be used to demonstrate electric fields. By rubbing the balloon on hair or other surfaces to create a charge, then holding it near small objects, such as paper or water droplets, you can see the effect of the electric field on these objects.

## 5. How does the size and shape of a rubber balloon affect its behavior in an electric field?

The size and shape of a rubber balloon can affect its behavior in an electric field. A larger balloon will experience a greater force in the electric field, causing it to stretch more. The shape of the balloon can also affect how the force is distributed, leading to different patterns of deformation.

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