14. Two small spherical balls each carrying a charge Q=10 pc
are suspended by two insulating threads of equal lengths
Im each, from a point fixed in the ceiling. It is found that in
equilibrium threads are separated by an angle 60° between
them, as shown in Fig. 1.75. What is the tension in the
threads? (Given that 1/4ne = 9 x 109 Nm/C/=in.)
Answers
Given,
Two small spherical balls each carrying a charge Q =10 pC are suspended by two insulating threads of equal lengths 1 m each, from a point fixed in the ceiling. It is found that in equilibrium threads are separated by an angle 60° between them.
To find,
the tension in the threads.
see figure,
horizontal component of tension = Tsin30° = T/2
electric force acting on each ball, F = KQ²/x²
[where x = 2lcos60° = 2 × 1 × 1/2 = 1 m ]
at equilibrium,
horizontal component of tension = electric force
⇒√3T/2 = kQ²/x²
⇒T/2 = {9 × 10^9 × (10 × 10¯¹²)²}/(1)²
⇒T/2 = (9 × 10¯¹³)
⇒T = 1.8 × 10¯¹² N
therefore tension in the threads is 18 × 10¯¹² N
Answer:
answer is 1.8N.... rest in the attachment.
...here in answer charge taken is 10 microcolumb=(10×10-⁶ C)
in question it is 10pico coloumb=10×10-¹²C
