Answer: b. 9.4 x 10^2 N/C
Step-by-step explanation:
The formula for calculating electric field strength, E at a point, X a distance of d from a charge is expressed as
E = kq/d^2
where
k is the electrostatic constant and its value is 9 x 10^9 N/m^2C^2
q is the magnitude of the charge in coulombs
From the information given
q = 1.5 nC
Recall,
1 nC = 1 x 10^- 9 C
1.5 nC = 1.5 x 1 x 10^- 9 = 1.5 x 10^-9 C
q = 1.5 x 10^-9 C
d = 12 cm
We would convert 12 cm to meters
Recall, 100 cm = 1m
12 cm = 12/100 = 0.12 m
d = 0.12 m
By substituting these values into the formula,
E = (9 x 10^9 x 1.5 x 10^-9)/0.12^2
E = 937.5
Rounding to the nearest ten, it becomes
E = 940 = 9.4 x 10^2
The answer is
b. 9.4 x 10^2 N/C