Figure shows two coherent sources $S_1\text{ and }{S}_2$ vibrating in same phase. AB is an irregular wire lying at a far distance from the source ${\mathrm{S}}_1\text{ and }{\mathrm{S}}_2\text{. Let }\lambda /\mathrm{d}={10}^{-3}\text{. }$ $\mathrm{\angle }\mathrm{BOA}={0.12}^{\circ }$. How many bright spots will be seen on the wire, including points A and B?

Angular width $=\lambda /\mathrm{d}={10}^{-3}\text{ (given) }$
Number of fringes within 0.06° will be $\frac{0.06\times \pi }{360\times {10}^{-3}}\cong \left[1.046\right]$
There is one bright fringe as we go towards A. Similarly  there is one bright fringe as we go towards B and one  bright fringe is at center (at point O).
Total number of Bright fringes =3