One particle has a charge of [tex]$2.15 \times 10^{-9} \, C$[/tex], while another particle has a charge of [tex]$3.22 \times 10^{-9} \, C$[/tex]. If the two particles are separated by 0.015 m, what is the electromagnetic force between them?

The equation for Coulomb's law is:

[tex]\[ F_e = \frac{k q_1 q_2}{r^2} \][/tex]

where the constant [tex]\( k \)[/tex] equals [tex]\( 9.00 \times 10^9 \, \text{N} \cdot \text{m}^2 / \text{C}^2 \)[/tex].

A. [tex]$4.31 \times 10^{-7} \, N$[/tex]

B. [tex]$2.77 \times 10^{-4} \, N$[/tex]

C. [tex]$6.22 \times 10^{-4} \, N$[/tex]



Answer :

To determine the electromagnetic force [tex]\( F_e \)[/tex] between two particles using Coulomb's law, we follow these steps:

1. Identify the given values:
- Charge of the first particle, [tex]\( q_1 = 2.15 \times 10^{-9} \, \text{C} \)[/tex]
- Charge of the second particle, [tex]\( q_2 = 3.22 \times 10^{-9} \, \text{C} \)[/tex]
- Separation distance, [tex]\( r = 0.015 \, \text{m} \)[/tex]
- Coulomb’s constant, [tex]\( k = 9.00 \times 10^9 \, \text{N} \cdot \text{m}^2 / \text{C}^2 \)[/tex]

2. Write Coulomb's law equation:
[tex]\[ F_e = \frac{k q_1 q_2}{r^2} \][/tex]

3. Substitute the given values into the equation:
[tex]\[ F_e = \frac{(9.00 \times 10^9) (2.15 \times 10^{-9}) (3.22 \times 10^{-9})}{(0.015)^2} \][/tex]

4. Calculate the denominator [tex]\( r^2 \)[/tex]:
[tex]\[ r^2 = (0.015)^2 = 0.000225 \, \text{m}^2 \][/tex]

5. Calculate the numerator [tex]\( k \times q_1 \times q_2 \)[/tex]:
[tex]\[ k \times q_1 \times q_2 = (9.00 \times 10^9) \times (2.15 \times 10^{-9}) \times (3.22 \times 10^{-9}) \][/tex]

6. Perform the multiplication in the numerator:
[tex]\[ (2.15 \times 10^{-9}) \times (3.22 \times 10^{-9}) = 6.913 \times 10^{-18} \][/tex]
[tex]\[ 9.00 \times 10^9 \times 6.913 \times 10^{-18} = 6.2217 \times 10^{-8} \][/tex]

7. Now, divide the result by the denominator [tex]\( r^2 \)[/tex]:
[tex]\[ F_e = \frac{6.2217 \times 10^{-8}}{0.000225} \][/tex]

8. Perform the division:
[tex]\[ F_e = 0.00027691999999999994 \, \text{N} \][/tex]

This value is approximately [tex]\(2.77 \times 10^{-4}\)[/tex] N when rounded appropriately.

Thus, the answer is:
B. [tex]\(2.77 \times 10^{-4}\)[/tex] N