The time required for half of a radioactive substance to decay, or more generally, for a quantity to reduce to half its initial value.
Half-life (t½) is the time for a quantity to decrease by 50%. It applies to radioactive decay, drug metabolism, and chemical reactions.
N(t) = N₀ × (1/2)^(t/t½), where N₀ = initial quantity, t = elapsed time.
After 10 half-lives, only 0.1% of the original quantity remains.
The relationship between voltage, current, and resistance in an electrical circuit: V = I × R.
A unit of energy equal to using 1,000 watts of power for one hour.
A rotational force that causes an object to rotate around an axis, measured in newton-meters or foot-pounds.
A unit of heat energy equal to the amount needed to raise one pound of water by one degree Fahrenheit.
A material property that measures how well it conducts heat, expressed in watts per meter-kelvin (W/m·K).
The amount of heat energy required to raise the temperature of one unit mass of a substance by one degree.