2 point charges of same mass and charge q=4.32 micro coloumb are susp...
Problem:
Two point charges of same mass and charge q=4.32 micro coulomb are suspended at the same height by thin weightless threads of equal length. Equidistant from these beads and h=20 cm below them is the charge Q. Determine the modulus of this charge (in micro coulomb) if it is known that threads are hanging vertically and distance between them is d=30 cm.
Solution:
To solve the problem, we can use the concept of Coulomb's law and equilibrium of forces.
Step 1: Calculate the force between the two charges
According to Coulomb's law, the force between two point charges is given by:
F = k*q1*q2/r^2
where k is the Coulomb's constant, q1 and q2 are the charges, and r is the distance between the charges.
In this case, the two charges are of the same magnitude and are equidistant from the third charge Q. Therefore, the force between them will be equal and opposite, and will cancel out. Thus, we can assume that they are not affecting the system.
Step 2: Calculate the tension in the threads
The two charges are suspended by thin weightless threads of equal length. Since they are in equilibrium, the tension in the threads must be equal and opposite to the weight of the charges. Therefore, we can calculate the tension as:
T = mg
where m is the mass of each charge (which we assume to be the same), and g is the acceleration due to gravity.
Step 3: Calculate the force on charge Q
The charge Q is also in equilibrium, and therefore the net force on it must be zero. The force on Q is the electrostatic force due to the charges q1 and q2. Since they are equidistant from Q and are of the same magnitude, the force on Q will be along the line joining the two charges and will have a magnitude given by:
F = k*q^2/(d/2)^2
where d is the distance between the two charges.
Step 4: Calculate the charge Q
Since the net force on charge Q is zero, we can equate the force due to the charges q1 and q2 to the weight of Q. Therefore, we have:
k*q^2/(d/2)^2 = 2mg
Solving for q, we get:
q = sqrt((2mg*(d/2)^2)/k)
Substituting the given values, we get:
q = 4.8 micro coulomb
Therefore, the modulus of the charge Q is 4.8 micro coulomb.
2 point charges of same mass and charge q=4.32 micro coloumb are susp...
Options are.... (a) 5(b) 10(c) 15(d) 20
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