Final answer:
To find the electric field strength at the midpoint between two charges, we can use the formula for electric field. In this case, the charges are 7.5 nc and -2.9 nc, and the distance between them is 3.0 cm. By plugging these values into the formula, we get an electric field strength of 1.15 N/C.
Step-by-step explanation:
To find the electric field strength at the midpoint between the two charges, we can use the formula for electric field:
Electric field (E) = (k * q) / r^2
where k is the electrostatic constant (9 × 10^9 N m^2/C^2), q is the magnitude of the charge, and r is the distance between the charges.
In this case, the charges are 7.5 nc and -2.9 nc, and the distance between them is 3.0 cm. Let's calculate the electric field:
E = (k * q1) / r^2 + (k * q2) / r^2
E = (9 × 10^9 N m^2/C^2 * 7.5 nc) / (0.03 m)^2 + (9 × 10^9 N m^2/C^2 * -2.9 nc) / (0.03 m)^2
E = 1.875 N/C - 0.725 N/C
E = 1.15 N/C
Therefore, the electric field strength at the midpoint between the two charges is 1.15 N/C.