Question

A housefly walking across a clean surface can accumulate a significant positive or negative charge. In one experiment, the largest positive charge observed was +70 pC. A typical housefly has a mass of 12mg. A.) Explain how the housefly could accumulate an electric charge by walking across a surface? B.) What magnitude and direction electric field would be necessary to levitate a housefly with a maximum charge? Could such a field exist in air?

Answer 1

Answer:

1681714.28571 N/C

Yes it could exist

Explanation:

m = Mass of housefly = 12 m

q = Charge = 70 pC

g = Acceleration due to gravity = 9.81 m/s²

E = Electric field

When an object accumulates charge it means that it is gaining electrons making it negatively charged. This is the concept of static electricity.

Here, the electric force and the graviational force will balance each other

$F_e=W\\\Rightarrow qE=mg\\\Rightarrow E=\frac{mg}{q}\\\Rightarrow E=\frac{12\times 10^{-6}\times 9.81}{70\times 10^{-12}}\\\Rightarrow E=1681714.28571\ N/C$

1681714.28571 N/C of electric field would be required to levitate

The direction of the electric field would be upwards vertically.

In air the critical value of electric field is $3\times 10^6\ N/C$ which is more than the critical value of electric field in air. So, the electric field can exist.