An electric field E with an average magnitude of about 160 N/C points downward ...........................?

Question

An electric field E with an average magnitude of about 160 N/C points downward in the atmosphere near Earth's surface. We wish to "float" a sulfur sphere weighing 3.2 N in this field by charging the sphere. Whis is it impractical

Answer 1

To do so, we need to cancel gravity's effect on the sphere. so:

total force on the sphere = 0 = weight of sphere + effect of charge

weight of sphere= -3.2 N , so

0= -3.2 N + effect of charge

if the field is downward and we take it to be negative, the charge has to be positive for the ball to float. So

Effect of Charge= 3.2 N

Since the field has an average strength of 160 N/C, we can find out how may coulombs we need by:

3.2N = 160 N/C * X

X= 3.2/160 C = 0.02 C = 2x10E-2 C

also, from Voltage (volts) = energy (joules)/ Charge (Coulombs)

1 C= 1 J / V


assume we use a practical voltage of 500 V

0.02 C= Y/ 500 V
Y = 500 * 0.02 = 10 J

this amount of electrical energy is already very large, impractical to produce.

responder to rhsaunders, the 10 J by itself is not that large an amount of energy. However, since we are dealing with electrical energy, if we convert 10 J to electronvolts, we would get
6.241 x 10E19 eV. As you said, we cannot generate this large amount of electrical energy at a practical setup. Bottom line, we still agree that it is not practical. nice day to you.

Answer 2

Responder dennis_d_worm 's answer makes no sense; ten joules is not that much energy. Let's start over.

We need to place a charge on the sulfur sphere such that the electrostatic attraction created by that charge interacting with the defined field equals the weight of the sphere. To do this, we need to understand the electrostatic capacity of the sphere, which has a mass of 320 grams. The size of such a sphere will be on the order of ten centimeters diameter. To get the capacity, we multiply this by the permittivity of empty space, 8.85 E-12 farads/meter, and get a capacity of about one picofarad. A charge of 50 millicoulombs on such a capacitor equates to a voltage potential of 50 gigavolts, which is far too large to generate by any means now available. And even if you could generate it, it would quickly dissipate via corona discharge.
The human body, as a capacitor, has a capacitance of a few picofarads. This is not much, but is enough to cause a detectable glow if you hold one probe of a neon-lamp circuit tester in one hand and stick the other probe into a 120-volt outlet. The current flow generated by your body capacitance is enough to generate a faint glow; it is far too small to feel, let alone be dangerous. Exercise: calculate this current for a man 1.8 meters tall, under the conditions named.

Answer 3

In that case the charge on the ball sphere would be about 3.2N/160N/C = 0.02C. Maybe that amount of charge is too much for our body.