Answer:
The electric flux through the balloon remains unchanged.
Step-by-step explanation:
Letting half of the air out of the balloon will reduce the area of the balloon by 4 times its initial area. Also, since the area is reduced, then, the field lines passing through the balloon will then become closer, or technically increase by four times. The general effect is that there will be no change in the electric flux through the balloon due to the reduced radius.
Mathematically,
Ф = AE
where A is the area of the balloon
E is the electric field around the balloon
Ф is the electric flux around the balloon
If the radius is halved, then the area of the balloon is reduced by four times from A to A/4.
The field through the balloon also increase from E to 4E
The resulting electric flux due to these changes will be
Ф = A/4 * 4E = AE
Technically, the flux does not change.