Question

two unequal point charges repel each other with a force of 0.2 n when they are 10cm apart.find the force which exerts on the other when they are 1cm and 5cm

Answer 1

Answer:

Coulomb's laws of electrostatic force says that when we place two charges at a distance of r meters, and magnitudes of charges are respectively q1 and q2, then force of attraction (in case of unlike charges) or repulsion (in case of like charges) will be equal to:

F=Kq1q2/r2

Step: 2 Calculation

Given:

F=0.2N, r=10cm=0.1m

Required:

F1 (force at 1cm) and F5 (force at 5cm)

According to given values:

F=Kq1q2/r2

0.2=Kq1q2/(0.1)2

Kq1q2=0.2(0.1)2

Kq1q2=0.2(0.01)

Kq1q2=0.002 --- (i)

We have of find F1 and F2:

F1=Kq1q2/(0.01)2

according to equation (i) Kq1q2=0.002, so above equation becomes:

F1=(0.002)/(0.0001)

F1=20N (Ans)

Similiarly,

F5=Kq1q2/(0.05)2

F5=(0.002)/(0.0025)

F5=0.8N (Ans)