Category: Physics

What are excimer lasers used for? Excimer lasers are used, for example, in: Ophthalmology — to vaporize part of the surface layer of the cornea and thus reshape the cornea to correct refractive errors from myopia (nearsightedness), hyperopia (farsightedness), and astigmatism. Dermatology — to treat psoriasis and vitiligo. What is the basic principle of excimer […]

What is the difference between projectile and trajectory? Projectile motion is when an object moves in a bilaterally symmetrical, parabolic path. The path that the object follows is called its trajectory. Projectile motion only occurs when there is one force applied at the beginning, after which the only influence on the trajectory is that of […]

Can magenta ever appear green? Magenta absorbs its complementary color – green. Thus, green is subtracted from cyan light. That leaves blue light to be transmitted by the filter. For this reason, the filter will appear blue when illuminated with cyan light. What allows us to see green? Long wavelengths stimulate red cones. Short wavelengths […]

Can a bubble float high into the sky? The heavier carbon dioxide in the air around the bubble pushes up on the air trapped inside the bubble and off it goes. This upward force is called “buoyancy.” If you’ve ever watched a helium balloon or blimp go soaring off into the sky, you’ve already seen […]

Does the velocity of the center of mass change? The velocity of the system’s center of mass does not change, as long as the system is closed. The system moves as if all the mass is concentrated at a single point. Is the velocity of the center of mass constant? If a system experiences no […]

Can you tell which element an atom is if you know its charge and the number of electrons it has? The number of protons in one atom of an element determines the atom’s identity, and the number of electrons determines its electrical charge. The atomic number tells you the number of protons in one atom […]

Is an immunologist a doctor? An allergist / immunologist (commonly referred to as an allergist) is a physician specially trained to diagnose, treat and manage allergies, asthma and immunologic disorders including primary immunodeficiency disorders. What is being an immunologist like? What Does an Immunologist Do? Immunologists study, diagnose, treat, and help prevent immune system disorders […]

Can a theory be a law? A theory does not change into a scientific law with the accumulation of new or better evidence. A theory will always remain a theory; a law will always remain a law. Both theories and laws could potentially be falsified by countervailing evidence. Theories and laws are also distinct from […]

Is room temperature a controlled variable? However, a substance at room temperature is cooler than the body, so when it is applied to the body, it extracts heat, making it not thermal neutral and not a good control variable. Is constant a algebraic expression? Constants are the terms in the algebraic expression that contain only […]

How long does SPF 50 last on face? two hours What time of day can you stop wearing sunscreen? To protect against damage from the sun’s rays, it is important to avoid the sun between 10 a.m. and 4 p.m., when the sun’s rays are strongest; to wear protective clothing; and to use a sunscreen […]