Hinge for a lamp

A hinge for a lamp comprising:

• a first connector on an upper end of a lamp pole, defining a circular groove therein;
• a second connector having a pivotal portion pivotally engaging the first connector and a mounting portion adapted for connecting with a lamp head of the lamp, the pivotal portion defining a curved groove therein, the curved groove being longer than a half of a perimeter of an annulus where the curved groove is distributed, the mounting portion defining a central hole therein;
• and
• a plurality of ball bearings movably sandwiched between the pivotal portion of the second connector and the first connector and received in the circular groove and the curved groove, the ball bearings separating the first connector from the second connector to define a space therebetween, a gap being defined between two neighboring ones of the ball bearings, the gap providing passage adapted for electric wires of the lamp to extend therethrough, the gap communicating with the central hole of the mounting portion of the second connector;
• wherein the second connector comprises a U-shaped pivotal portion extending from the mounting portion, with the curved groove defined at a side face of the pivotal portion.