A lamp has multiple arms and multiple hinges mounted between two adjacent arms. The hinge has a stationary leaf, multiple pivot assemblies being mounted in the stationary leaf and multiple brackets being respectively connected to the pivot assemblies and two corresponding brackets are attached to each arm. Each pivot assembly has a shaft and a locking nut being mounted on the shaft and selectively engaging a locking hole of each bracket. Since the locking nuts selectively engage the locking holes of the brackets, an angle between the adjacent arms can be adjusted and fixed. Further, two adjacent arms do not influence each other's position, which is convenient for adjusting.