Category: Physics

What did they use for light in 1600s? Medieval lighting came from large central fireplaces, candles, rush lights, flaming torches or lanterns. Candles, which had been around since Roman times, were made from animal fat, or beeswax if you were wealthy. How did people light candle chandeliers? The very wealthy used high grade beeswax candles, […]

Is the atomic number the number of electrons? The atomic number uniquely identifies a chemical element. It is identical to the charge number of the nucleus. In an uncharged atom, the atomic number is also equal to the number of electrons. The sum of the atomic number Z and the number of neutrons N gives […]

What keeps the sun from exploding? The inward pressure that keeps a star from exploding is the gravitational attraction of the gas mantle surrounding the core (which is most of the volume of the Sun, and is very hot but does not burn itself). Why does the sun not explode like a hydrogen bomb? The […]

Should you put plastic behind insulation? Without a vapor barrier in place, condensation inside the walls could ruin the insulation and promote the growth of harmful mold and bacteria. Plastic, specifically 6-mil polyethylene plastic, is the most commonly used vapor barrier. Should you put plastic over insulation before drywall? Without poly beneath the drywall, water […]

How long should ice be used to reduce swelling? Cold will reduce pain and swelling. Apply an ice or cold pack right away to prevent or minimize swelling. Apply the ice or cold pack for 10 to 20 minutes, 3 or more times a day. What are puffy ankles a sign of? Common causes of […]

Why is potential energy negative in an atom? When a stable atom is formed, the electron is attracted to the nucleus, r is less than infinity, and the energy will be negative. A negative value for the energy implies that energy must be supplied to the system if the electron is to overcome the attractive […]

What is full form of SI unit? Système international What is called 1 unit? A unit is any measurement that there is 1 of. So 1 meter is a unit. And 1 second is also a unit. And 1 m/s (one meter per second) is also a unit, because there is one of it. What […]

What is the most calming color to paint a bedroom? For a relaxing atmosphere in your bedroom, look to cooler hues — shades of gray, blue, green and purple — to lend a hand. These colors have been shown to reduce stress and anxiety. They can also make a space seem more expansive, so they’re […]

Can dolphins kill you? THEY may have a reputation for being friendly, cute and curious creatures, but dolphins can also be extremely vicious – and attacks on humans are on the rise. Just last month, 10-year-old Lexi Yeo was savaged by a pair of captive bottlenose dolphins, while on a swim experience in Cancun, Mexico. […]

What is the reading on the vernier calipers? The main scale reading is the first reading on the main scale immediately to the left of the zero of the vernier scale (3 mm), while the vernier scale reading is the mark on the vernier scale which exactly coincides with a mark on the main scale […]