Question

Explain how you can determine how much power a circuit will generate if you know the voltage and resistance but not the current

Answer 1

To calculate the power in a circuit using known voltage and resistance, use the equation P = V² / R, derived from Ohm's law. This allows for power calculation without direct current measurement, as resistance is the main determinant of power dissipation.

Step-by-step explanation:

To determine the amount of power a circuit will generate based on the known voltage and resistance, you can use a version of the power equation derived from Ohm's law. Ohm's law states that V = IR (Voltage equals current times resistance). Using this, we can rearrange the original power equation P = IV (Power equals current times voltage) by substituting current with V/R from Ohm's law. This gives us an equation for power solely in terms of voltage and resistance: P = V² / R.

This means if you know the voltage across and the resistance of a circuit, you can calculate the power without knowing the current directly. For example, if a circuit has a voltage source of 100 volts and a 25-ohm resistor, the power dissipated by the resistor can be calculated as follows: P = 100² / 25, which equals 400 watts.

It's important to understand that the resistance is the physical characteristic that determines how much power is dissipated in a circuit, making these calculations very useful when dealing with resistive elements like heaters or light bulbs.

Answer 2

Power can be found using the equation: power = (voltage)2 / resistance.

The general formula for power dissipation is:
Power = Current x Voltage
However, if you only know the voltage and the resistance, you can calculate the current using Ohm's Law, which is usually given as:
Voltage = Current x Resistance
However, you can rearrange this to give:
Current = Voltage/Resistance
You can then substitute this into the expression for power dissipation to yield an equation that gives an expression for power in terms of only voltage and resistance:
Power = / Resistance