The strength of an electric field at 5.0 cm from a point charge is 100.0 N/C. What is the magnitude of the source charge? Show work so I understand how to do it.
E=kQ/r^2
solve for Q, you have r, E
What do I do NOW? I am lost
Well, you basically told me the answer.
E = k Q / r^2
so
Q = r^2 E / k
here
r = .05 meters so r^2 = 25 * 10*-4 m^2
E = 100 N/C
k = 9 * 10^9 N m^2/C^2
To find the magnitude of the source charge, you need to rearrange the equation E=kQ/r^2 to solve for Q.
1. Start with the equation: E = kQ/r^2
2. Rewrite the equation as Q = (E * r^2) / k
3. Plug in the given values into the equation:
- E = 100.0 N/C (electric field strength)
- r = 5.0 cm = 0.05 m (distance from the point charge)
- k = 8.99 x 10^9 Nm^2/C^2 (Coulomb's constant)
4. Substitute the values into the equation Q = (E * r^2) / k:
Q = (100.0 N/C * (0.05 m)^2) / (8.99 x 10^9 Nm^2/C^2)
5. Now, calculate the magnitude of the source charge using a calculator:
Q ≈ 0.00011123 C
(Note: C represents Coulombs, the unit of charge)
Therefore, the magnitude of the source charge is approximately 0.00011123 Coulombs.