When a particle and an antiparticle come together, they a. annihilate each other, releasing photons. b. create a black hole. c. release astronomical amounts of energy. d. create new particles.

When a particle and its corresponding antiparticle come together, they undergo a process known as annihilation. During this event, the mass of both the particle and the antiparticle is converted into energy. This energy is often released in the form of photons. These photons are particles of light and are part of the electromagnetic spectrum. In simpler terms, when particles annihilate, they vanish and create light particles, or photons, which carry away the energy that was held in the mass of the original particles.
This release of photons ensures that the energy remains conserved in the system. The concept is crucial to understanding various physical phenomena, such as the processes occurring in particle accelerators and certain types of radioactive decay.

Mass-energy equivalence is one of the cornerstones of modern physics, encapsulated by Albert Einstein's famous equation: E = mc^2. This formula implies that mass can be converted into energy and vice versa. In the context of particle-antiparticle annihilation, the mass of both particles is fully transformed into energy.
Here, 'E' represents energy, 'm' denotes mass, and 'c' is the speed of light in a vacuum, approximately 3 x 10^8 meters per second. The speed of light is squared, which means even a small amount of mass can be converted into a large amount of energy.
This principle helps us understand the energy output from atomic processes, such as what happens in nuclear reactors, where a tiny amount of mass loss translates into significant energy release. It's also essential for technologies like PET scans and has broad implications in cosmology.

Electromagnetic radiation encompasses a spectrum of waves ranging from very low-frequency radio waves to high-frequency gamma rays. Photons released during particle-antiparticle annihilation fall under this category.
Depending on the energy levels involved in the annihilation, the photons can be visible light, X-rays, or even gamma rays. The key point is that all these forms of radiation travel at the speed of light and carry energy away from the annihilation event.
Electromagnetic radiation is essential in various fields. For instance, it's fundamental to the operation of devices like microwaves, X-ray machines, and communication technologies like Wi-Fi and mobile phones. It also plays a crucial role in many natural phenomena, such as solar radiation reaching Earth and the cosmic microwave background radiation stemming from the Big Bang.