For any given substance, the heat capacity of a body is directly proportional to the amount of substance it contains (measured in terms of mass or moles or volume). Doubling the amount of substance in a body doubles its heat capacity, etc.
Conventional soft contacts can last up to a year; conventional rigid gas permeable (RGP) contact lenses can last even longer. Frequent or planned replacement contact lenses last one to several months. Disposable contacts last from one day (daily wear) to up to two weeks (extended wear).
Quote: Originally Posted by Pete Teoh I was told that contact lens prescriptions are good for 1 year, while spectacles are good for 2. ah, that could be true. I posted the 2 year thing by looking at the prescription for my eyeglasses which was in my wallet.