How does phototropism occur in plants?

Explanation

The bending of a plant stem towards light is an example of phototropism. The plant stem responds to light and bends towards it due to the action of 'auxin hormone'. This happens as follows : The auxin hormone is present in the tip of the stem of the growing plant. The auxin hormone present in to stay in shade, away from light. So, when sunlight falls on the side of the stem which is away from light. Auxin promotes growth. So, due to more auxin, the shady side of stem (which is away from light) grows to be longer than the stem bend towards light. For example, in Figure given here, the left side A of the stem (which is away from light) has more auxin hormone and frows faster than right side B which is towards light. Since side A of stem becomes longer than side B, the stem bends towards right side (in the direction of light).