Category: Physics

What describes a concave lens? A concave lens is a lens that possesses at least one surface that curves inwards. It is a diverging lens, meaning that it spreads out light rays that have been refracted through it. A concave lens is thinner at its centre than at its edges, and is used to correct […]

What are the risks of using iodine-131? I-131 collects in the thyroid gland. People exposed to I-131, especially during childhood, may have an increased risk of thyroid disease, including thyroid cancer. Thyroid cancer is uncommon and is usually curable. Typically, it is a slow-growing cancer that is highly treatable. What percentage of an original sample […]

What is relation between CP and CV? The specific heat of gas at constant volume in terms of degree of freedom ‘f’ is given as: Cv = (f/2) R. So, we can also say that, Cp/Cv = (1 + 2/f), where f is degree of freedom. Monoatomic gas has only one translational motion, hence three […]

How long does it take for carbon 14 to fully decay? 5,730 years Will all of Carbon 14 eventually disappear? The half-life of carbon-14 is the amount of time it takes for one-half of the original amount to disappear by radioactive decay. After 50,000 years, a fossil won’t have any radiocarbon left in it. Carbon-14 […]

What does 1 dB mean? Decibel How does dB loss work? dB (decibel) Every time you double (or halve) the power level, you add (or subtract) 3 dB to the power level. This corresponds to a 50 percent gain or reduction. 10 dB loss corresponds to a tenfold decrease in signal level. A 20 dB […]

What vehicles must stop at all railroad crossings NY DMV? Most buses and some trucks must stop at railroad crossings. (See “Railroad Crossing Signals”.) Flashing red lights, lowered crossing gates and/or a bell at a railroad crossing indicate that you must stop, at least 15 feet (5 m) from the tracks. What is the appropriate […]

Is 25 miles per hour wind fast? – at 19 to 24 mph, smaller trees begin to sway. – at 25 to 31 mph, large branches will be in motion, whistling will be heard in overhead wires, and umbrella use becomes difficult if not impossible. – at 32 to 38 mph, whole trees will be […]

What is the significance of knowing strengths and weaknesses of a research work? Knowing your weaknesses allows you to understand how you can work around them. Strengths and weaknesses are part of being self-aware. When you know your strengths and weaknesses, you can create a development strategy that focuses on your specific development needs. What […]

Why is there vacuum above the level of mercury in a mercury barometer? The top of the barometer is filled with nothing (vacuum) because the mercury must have the space to expand and contract without any other force affecting it; a gas or liquid in the top would have its own pressure against the mercury […]

What holds a nucleus together? The strong nuclear force. At extremely short range, it is stronger than electrostatic repulsion, and allows protons to stick together in a nucleus even though their charges repel each other. Remember that the size of the nucleus is really small compared to the size of an atom. What makes a […]