Open the Ohm's Law Calculator. Enter your supply voltage (e.g., 5V), the LED forward voltage (e.g., 2V), and the desired current (e.g., 20mA). The calculator gives the required resistance (150Ω). Round up to the nearest standard resistor value.

The RC time constant (τ = R × C) is the time it takes a capacitor to charge to 63.2% of the supply voltage through a resistor. After 5τ it is essentially fully charged. Matters for filter design, timing circuits, and sensor debouncing.

Yes. The Unit Converter covers volume units including millilitres, fluid ounces, cups, tablespoons, and teaspoons — perfect for recipe scaling between metric and imperial.

N(t) = N₀ × (½)^(t/t₂) — where N₀ is the starting quantity, t is elapsed time, and t₂ is the half-life period. Enter any three of the four values and the calculator solves for the missing one.

They are inversely proportional: wavelength = speed ÷ frequency. For light in a vacuum, speed is fixed at ~3×10⁸ m/s. So higher-frequency light (violet) has shorter wavelength than lower-frequency light (red).