Electric work machine and screwing tool

An electric work machine, comprising:

• a motor including a rotor rotatable about a rotation axis;
• an output unit located toward a first end of the electric work machine relative to the motor and operable under a rotational force from the rotor;
• a light emitter;
• and
• an optical member including
• at least one light receiver configured to receive light from the light emitter, and
• a light guide surrounding at least a part of the output unit to allow light from the at least one light receiver to travel through the light guide, the light guide having a second guide surface having at least one slit, and a first guide surface to allow emission of light traveling through the light guide and reflected at the at least one slit,
• wherein
• the at least one slit is defined by a first slit surface and a second slit surface located farther from the at least one light receiver than the first slit surface and facing the first slit surface across an opening of the at least one slit,
• the first slit surface totally reflects a part of light traveling through the light guide, and
• the second slit surface is a flat surface parallel to a first axis and to a radial axis, where the first axis is parallel to the rotation axis, and the radial axis extends radially from the rotation axis.