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1) Consider two charged objects lying along the x-axis. A 2.0 x 10 -9 C point ch

ID: 1404365 • Letter: 1

Question

1) Consider two charged objects lying along the x-axis. A 2.0 x 10-9 C point charge is located at x = 3.0 cm and a -3.0 x 10-9 C point charge is located at x = 5.0 cm.

a) What is the magnitude of the force on the negatively charged object due to the positively charged object? What is its direction? Show your work and explain your reasoning.

b) Suppose the -3.0 X10-9 C charge is moved to x = 5.0 cm and y = 6.0 cm. What is the magnitude of the force exerted by the negative point charge on the positive point charge? What is its direction? Show your work and explain your reasoning.

Explanation / Answer

Q1 = 2.0 * 10^-9 C
Q1 = -3.0 * 10^-9 C

a)
Magnitude of Force = k Q1Q2/r2
where K = 8.9 * 10^9 N m^2/C^2
r = distance between charges = 5 - 3 = 2cm = 2 * 10^-2 m

F = (8.9 * 10^9 * 2.0 * 10^-9 3.0 * 10^-9 ) / (2 * 10^-2)^2
F = 1.34 * 10^-4 N
Magnitude of the force on the negatively charged object F = 1.34 * 10^-4 N

Direction of foce is towards left, Reason - unlike charges attract each other.

b)
Magnitude of Force = k Q1Q2/r2
r = distance between charges = sqrt ((5-2)^2 + (6-0)^2)
r = 6.71 * 10^-2 m

F = (8.9 * 10^9 * 2.0 * 10^-9 3.0 * 10^-9 ) / (6.71 * 10^-2)^2
F = 1.19 * 10^-5 N
Magnitude of the force on the negatively charged object F = 1.19 * 10^-5 N

Direction of Force =
= tan^-1 (6/2)
= 71.57o from +ve X axis in anti-clockwise direction.
Direction of Force = 71.57o from +ve X axis in anti-clockwise direction.