Electrostatic force – problems and solutions
1. Kung ang static electric force is 144 N, what is the distance between both naglo-load… (1 µC = 10-6 C and k = 9.109 Nm2.C-2)
Kilala:
Puwersa ng kuryente (F12) = 144 N
Singil 1 (q1) = 10 µC = 10 x 10-6 C
Singil 2 (q2) = 4 µC = 4 x 10-6 C
Constant (k) = 9 10 x9 Nm2.C-2
C = Coulomb, N = Newton, m = metro
Hinahanap: Distance between both charges (r)
solusyon:
Ang ekwasyon ng Batas ng Coulomb :
F = the static electric force, k = Coulomb’s constant, q = electric charge, r = distance between both charges
Distance between both charges (r) = 5 x 10-2 metro = 5 x 10-2 x 102 cm = 5 cm.
2. Two charges separated by a distance of r. If the static electric force is 3.6 N, what is the distance between both charges (1 µC = 10-6 C at k = 9.109 Nm2.C-2)
Kilala:
Electric force (F12) = 3.6 N
Singil 1 (q1) = 9 µC = 9 x 10-6 C
Singil 2 (q2) = 4 µC = 4 x 10-6 C
Coulomb’s constant (k) = 9 10 x9 Nm2.C-2
C = Coulomb, N = Newton, m = metro
Hinahanap: Distance between both charges (r)
solusyon:
Distance between both charges (r) = 0.3 m = 0.3 x 100 cm = 30 cm.
3. Three point charges as shown in figure below. What is the magnitude of the static electric force at point A (k = 9.109 Nm2.C-2; 1 μ = 10-6)
Kilala:
Bayad Isang (q)A) = -2 µC = -2 x 10-6 C
Bayad B (q)B) = 8 µC = 8 x 10-6 C
Bayad C (qC) = 4,5 µC = 4,5 x 10-6 C
Coulombpare-pareho (k) = 9 10 x9 Nm2.C-2
Distance between charge A and B (rAB) = 4 sentimetro = 4 x 10-2 m
Distance between charge A and C (rAC) = 3 sentimetro = 3 x 10-2 m
C = Coulomb, N = Newton, m = metro
Hinahanap: The static electric force at point A
solusyon:
The equation of Coulomb’s law :
F= the static electric force, k = Coulombpare-pareho, q = electric charge, r = distance between both charges
The static electric force at point A :
4. Three-point charges as shown in the figure below. What is the magnitude of Coulomb force experienced by Charge B (k = 9.109 Nm2.C-2; 1 µC = 10-6 C).
Kilala:
qA = 10 µC = 10 x 10-6 C = 10-5 Coulomb
qB = 10 µC = 10 x 10-6 = 10-5 Coulomb
qC = 20 µC = 20 x 10-6 = 2x10-5 Coulomb
rAB = 0.1 meter = 10-1 m
rBC = 0.1 meter = 10-1 m
k = 9 x 109 Nm2C-2
Hinahanap: Coulomb force experienced by Charge B
solusyon:
There are two coulomb forces act on charge B, Coulomb force between charge A and B (FAB) and Coulomb force between charge B and C (FBC). Coulomb force experienced by charge B is net force of FAB at FBC.
Coulomb force between charge A and B :
Charge A signed positive and charge B signed positive so that FAB points to charge C.
Coulomb force between charge B and C :
Charge B signed positive and charge C signed positive so that FBC points to charge A.
Coulomb force experienced by charge B :
FB =FBC - FAB = 180 – 90 = 90 N
Coulomb force experienced by charge B (FB) is 90 Newton. The direction of FB same as the direction of FBC points to charge A.
5. Determine the magnitude and direction of Coulomb force on charge B (k = 9 x 109 Nm2C-2, 1 µC = 10-6 C).
Kilala:
Bayad Isang (q)A) = +Q
Bayad B (q)B) = -2Q
Bayad C (qC) = -Q
Distance between charge A and B (rAB) = r
Distance between charge B and C (rBC) = 2r
k = 9 x 109 Nm2C-2
Hinahanap: Magnitude and direction of Coulomb force on charge B
solusyon:
Coulomb force between charge A and B :
Charge A positive and charge B negative so that the direction of FAB points to charge A.
Coulomb force between charge B and charge C :
Charge B is negative and charge C is negative so that the direction of FBC points to charge A.
Net force act on charge B :
F = FAB +FBC = 2 kQ2/r2 + 0.5 kQ2/r2 = 2.5 kQ2/r2 = 2.5 kQ2 r-2
Direction of force points to charge A or to leftward.
