The correct option is (C)
Six point charges are kept \(60^\circ\) apart from each other on the circumference of a circle of radius \( R \) as shown in figure. The net electric field at the center of the circle is ___________. (\( \varepsilon_0 \) is permittivity of free space) 
A Wheatstone bridge is initially at room temperature and all arms of the bridge have same value of resistances \[ (R_1=R_2=R_3=R_4). \] When \(R_3\) resistance is heated, its resistance value increases by \(10%\). The potential difference \((V_a-V_b)\) after \(R_3\) is heated is _______ V. 
