Science & Electronics calculators

Only to purely resistive, linear components: a plain resistor, for instance. Components like diodes, transistors and many real-world loads have a voltage-current relationship that isn't a straight line, so Ohm's law doesn't directly describe them.

A thinner wire (higher AWG number) has more electrical resistance per foot than a thicker one. So it dissipates more voltage as heat over the same run length and current. Long runs or high currents need a thicker gauge to keep voltage drop within an acceptable range.

How dense a substance is relative to water. A specific gravity above 1 means it's denser than water and will sink in it. Below 1 means it's less dense and will float. It's a quick, unit-independent way to compare materials.

Yes, slightly: liquids expand as they warm, increasing the solution's volume without changing the amount of dissolved solute, which lowers the molarity. This is why precise chemistry work specifies the temperature a molarity was measured or prepared at.

After each half-life, half of what remains decays, so the amount approaches zero without reaching it. In practice a sample counts as gone when too little is left to matter or to detect.

Hydrogen ion concentrations span many orders of magnitude, from about 1 mole per liter in strong acid to 10 to the minus 14 in strong base. A log scale squeezes that into 0 to 14, and each unit is a factor of ten.

Each added path gives current another route, so more current flows at the same voltage. More current at the same voltage means lower resistance overall.

Put the measured stock volume in a container, then add diluent up to the final volume mark, instead of adding a fixed volume of water. Filling to the mark keeps the final volume, and so the concentration, correct.

By convention the tolerance band is set apart from the other bands, so you read from the other end. Gold and silver, the usual tolerance colors, are never used as the first digit.

It uses two resistors in series to drop a voltage to a fraction of the input. It suits signals and sensor inputs. It is a poor way to power anything because it wastes energy and sags under load.

A motor's power factor is below 100 percent, so it draws extra current that does no useful work. Starting a motor can also draw several times the running current for a moment.

No. It assumes a fixed amount of gas. If gas is added or lost, the ideal gas law with the amount of gas as a variable is the right tool.

Subtract the LED's forward voltage from the supply voltage and divide by the desired current, for example 20 milliamps.

The number of moles of solute per liter of solution, so a one molar solution contains one mole of the substance in each liter.

The time for a capacitor to charge to about 63% of the supply voltage, found by multiplying the resistance by the capacitance.