The ornamental design for a movablereflector for a light bulb, as shown and described.
FIG. 1 is a top perspective view of a movable reflector for a light bulb shown in a first position within a light bulb, showing my new design;
FIG. 2 shows the movable reflector for a light bulb in a second position, which is to the left of the first position;
FIG. 3 shows the movable reflector for a light bulb in a third position, which is to the left of the second position;
FIG. 4 shows the movable reflector for a light bulb in a fourth position, which is to the left of the third position;
FIG. 5 shows the movable reflector for a light bulb in a fifth position, which is to the left of the fourth position; and,
FIG. 6 shows the movable reflector for a light bulb in a sixth position, which is to the left of the fifth position.
As shown in the figures, the movable reflector for a light bulb can move from the right to the left. The reflector can move to nearly any position within a bulb housing. The drawings are not meant as limitations on the positions of the reflector within a bulb, as the positions of the reflector within a bulb are not exhaustive.
The broken line showing on the drawing disclosure is for illustrative purposes only and forms no part of the claimed design.