At what angle will a small ball with a charge of 4 ∙ 10 ^ -7 C weighing 4 mg, suspended on a silk thread, deviate

At what angle will a small ball with a charge of 4 ∙ 10 ^ -7 C weighing 4 mg, suspended on a silk thread, deviate from the vertical if it is placed in a horizontal uniform electric field with an intensity of 100 N / C?

To solve the problem, you need to use the following formula:
m * q * tan α = Fel;
Let’s transform the formula for finding F:
Fel = q * E;
Thus, we get:
m * g * tan α = E * q;
You need to find tg a, the following formula:
tg α = E * q / m * g;
Substitute the value and calculate:
tg a = 100 * 4 * 10 ^ -7 / 4 * 10 * 10 ^ -6;
tg a = 1;
Let’s find a:
α = 45 °;
Answer: α = 45 °.