Albert Einstein made a huge impact on how we think about light and energy. Before him, people mainly believed that light was just a wave. But in 1905, Einstein came up with a new idea: light also acts like a tiny particle. He called these particles "quanta," but we mainly know them as "photons."
Quantum Idea: Einstein proposed that light is made up of little packets of energy. The energy of each photon is related to its frequency, which is how often the light waves move up and down. This can be written as: Here, is a special number known as Planck’s constant, which is about . This idea was a big deal because it helped explain the photoelectric effect.
Understanding the Photoelectric Effect: According to Einstein, when light hits a metal surface, it can kick out electrons. However, this only happens if the light has enough energy. If the energy of the photon is greater than the minimum needed to release an electron (this minimum is called the work function), the electron will be emitted. This means not all types of light can do this—only light with a certain amount of energy can.
Testing the Theory: Einstein's ideas were backed up by experiments. A key experiment was done by Robert Millikan in the 1910s. Millikan’s famous oil-drop experiment showed that there was a clear link between the stopping voltage and the frequency of the incoming light, supporting Einstein's theory.
Einstein's research on the photoelectric effect helped to show that light has two main behaviors: it can act like a wave and also like a particle. This was key to the development of quantum mechanics, which is a big part of modern physics. His discoveries were the start of a new understanding of the universe, focusing on the role of photons and laying the groundwork for future ideas in science that are still important today.
Albert Einstein made a huge impact on how we think about light and energy. Before him, people mainly believed that light was just a wave. But in 1905, Einstein came up with a new idea: light also acts like a tiny particle. He called these particles "quanta," but we mainly know them as "photons."
Quantum Idea: Einstein proposed that light is made up of little packets of energy. The energy of each photon is related to its frequency, which is how often the light waves move up and down. This can be written as: Here, is a special number known as Planck’s constant, which is about . This idea was a big deal because it helped explain the photoelectric effect.
Understanding the Photoelectric Effect: According to Einstein, when light hits a metal surface, it can kick out electrons. However, this only happens if the light has enough energy. If the energy of the photon is greater than the minimum needed to release an electron (this minimum is called the work function), the electron will be emitted. This means not all types of light can do this—only light with a certain amount of energy can.
Testing the Theory: Einstein's ideas were backed up by experiments. A key experiment was done by Robert Millikan in the 1910s. Millikan’s famous oil-drop experiment showed that there was a clear link between the stopping voltage and the frequency of the incoming light, supporting Einstein's theory.
Einstein's research on the photoelectric effect helped to show that light has two main behaviors: it can act like a wave and also like a particle. This was key to the development of quantum mechanics, which is a big part of modern physics. His discoveries were the start of a new understanding of the universe, focusing on the role of photons and laying the groundwork for future ideas in science that are still important today.