Question: Who is the child of the physicist who who developed an explanation for the photoelectric effect?

Knowledge 1: Photoelectric effect
In 1887, Heinrich Hertz discovered that electrodes illuminated with ultraviolet light create electric sparks more easily. In 1900, while studying black - body radiation, the German physicist Max Planck suggested that the energy carried by electromagnetic waves could only be released in ``packets ''of energy. In 1905, Albert Einstein published a paper advancing the hypothesis that light energy is carried in discrete quantized packets to explain experimental data from the photoelectric effect. This model contributed to the development of quantum mechanics. In 1914, Robert Millikan's experiment supported Einstein's model of the photoelectric effect. Einstein was awarded the Nobel Prize in 1921 for`` his discovery of the law of the photoelectric effect'', and Millikan was awarded the Nobel Prize in 1923 for ``his work on the elementary charge of electricity and on the photoelectric effect ''. [SEP] Knowledge 2: Evelyn Einstein
Evelyn Einstein (28 March 1941 – 13 April 2011) was the adopted daughter of Hans Albert Einstein, the son of Albert Einstein.
Knowledge 1: Planck constant
The photoelectric effect is the emission of electrons (called "photoelectrons") from a surface when light is shone on it. It was first observed by Alexandre Edmond Becquerel in 1839, although credit is usually reserved for Heinrich Hertz, who published the first thorough investigation in 1887. Another particularly thorough investigation was published by Philipp Lenard in 1902. Einstein's 1905 paper discussing the effect in terms of light quanta would earn him the Nobel Prize in 1921, when his predictions had been confirmed by the experimental work of Robert Andrews Millikan. The Nobel committee awarded the prize for his work on the photo-electric effect, rather than relativity, both because of a bias against purely theoretical physics not grounded in discovery or experiment, and dissent amongst its members as to the actual proof that relativity was real. [SEP] Knowledge 2: Evelyn Einstein
Evelyn Einstein (28 March 1941 – 13 April 2011) was the adopted daughter of Hans Albert Einstein, the son of Albert Einstein.
Knowledge 1: Planck constant
The photoelectric effect is the emission of electrons (called "photoelectrons") from a surface when light is shone on it. It was first observed by Alexandre Edmond Becquerel in 1839, although credit is usually reserved for Heinrich Hertz, who published the first thorough investigation in 1887. Another particularly thorough investigation was published by Philipp Lenard in 1902. Einstein's 1905 paper discussing the effect in terms of light quanta would earn him the Nobel Prize in 1921, when his predictions had been confirmed by the experimental work of Robert Andrews Millikan. The Nobel committee awarded the prize for his work on the photo-electric effect, rather than relativity, both because of a bias against purely theoretical physics not grounded in discovery or experiment, and dissent amongst its members as to the actual proof that relativity was real. [SEP] Knowledge 2: One-child policy
On October 29, 2015, it was reported that the existing law would be changed to a two - child policy, citing a statement from the Communist Party of China. The new law became effective on January 1, 2016, following its passage in the standing committee of the National People's Congress on December 27, 2015.

Answer: Hans Albert Einstein