Yes, light indeed affect the bending of the stems.This is because shoots usually move towards the light while roots usually move away from it and this apply in mung bean plant as it is also a plant.
When light comes from an angle, plants will curve toward it to get better access to the light they need to grow. Hormones in the plant's tissues, called auxins, make cells on the dark side of the plant grow taller, bending the plant toward the light.
