High School Physics : Electricity and Magnetism
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Example Question #962 : High School Physics
Kirchoff’s loop rule is an example of
None of the givens answers
Conservation of momentum
Conservation of charge
Conservation of energy
Conservation of energy
Kirchoff’s loop law states that the sum of the voltage around a loop must equal zero. In other words, the voltage that is being provided by the batteries in the circuit must equal the voltage being used by the objects in the circuit. Voltage is a measure of the potential difference, or energy within the circuit. In other words, the battery does a certain amount of work and provides energy to the circuit which is then used by all the parts of the circuit. Therefore this is an example of conservation of energy.
Example Question #963 : High School Physics
Calculate the voltage drop from point 
To begin we need to simplify the circuit to get the equivalent resistance. Let’s start with the 3 and 6 Ohm resistors in parallel.
Now we can add this resistor to the 4 Ohm resistor as they are in series.
We can now determine the current coming out of the battery using Ohm’s Law.
Rearrange to solve for current.
The current coming out of the battery will be the same current that moves through the 4 Ohm resistor. So we can determine the voltage drop across the 4 ohm resistor.
We can then use Kirchoff’s loop law to determine the voltage drop from point 
Let’s analyze the loop that goes from the battery to the 4 ohm resistor and through the 3 ohm resistor.
Example Question #964 : High School Physics
Which of the equations here is valid for the circuit shown?
To answer this question we must consider Kirchoff’s Loop Law. This law states that the voltage around any loop must equal 0. In this case there are two different loops at play. To begin, let’s start on the left with the 2 Volt battery.
As we start with the 2 Volt battery, we then move into the 1 Ohm resistor with 
We will continue our loop through the middle of the circuit into the 4 Volt battery. This battery is facing the opposite direction from our 2 Volt battery and therefore will be a negative when it comes to our equation.
Next is the 2 Ohm resistor with 
When summarizing all of these parts we get an equation that looks like 
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