Ohm's Law - AP Physics 1

First we need to calculate the equivalent resistance of the circuit using the following expression for condensing parallel resistors:

Now we can use Ohm's law to calculate the current flowing through the circuit:

First, identify the given information:

Two equations are required for this problem:

1.) Ohm's law,

2.) Electrical power

Using the equation for electrical power, we can rearrange to solve for :

At this point, we can substitute in the known values and determine the voltage:

Ohm's law can then be rearranged to solve for the resistence of the light bulb:

The known voltage value then can be substituted into Ohm's law to determine the resistance of the light bulb:

Use Ohm's law.

Plug in known values and solve for resistance.

Use Ohm's Law.

UseOhm's law.

Plug in known values and solve.

To find the current, first find the total resistance of the circuit. Begin by simplifying , the two resistors in parallel as follows:

Since and are in series, their combined resistance is:

Use Ohm's law to find the current.

Begin by finding the total resistance in the circuit.

Now note that the voltage identified in the problem is the same as the voltage drop across the second resistor:

Begin by finding the total resistance in the circuit.

Now note that the voltage identified in the problem is the same as the voltage drop across the second resistor:

Now, since and combine to form the total resistance:

Ohm's law states that the potential drop across a resistor is equal to the product of the current flowing through the resistor and the resistance of the resistor:

We were given the current, I, and the resistance, R, so we simply multiply the two together to get our final answer.

By Ohm's law:

, where is the voltage drop across the wire. is the current flowing through the wire, and is the total resistance within the circuit.

Since resistors are in series:

, where and are the resistances of the two resistors.

In our case:

Therefore:

This question can be solved by making use of Ohm's law, which states that the voltage difference across a circuit is proportional to the current flowing through the circuit, as well as to the resistance of the circuit. Written in equation form, we have:

Solving for current, we can rearrange to obtain:

We need to use Ohm's law here which is given by:

Where is the voltage in Volts, is the current in Amperes, and is the resistance in Ohms. We know the current in the circuit as well as the resistance of the resistor. We substitute our known values and solve for Voltage which will give us the voltage drop across the resistor.

We use Ohm's law, , to find the current in the circuit. In Ohm's law is the voltage in the circuit, is the current in the circuit and is the circuit's resistance.

Solving the equation for , we have

We use Ohm's law, , to find the current in the circuit. In Ohm's law is the voltage in the circuit, is the current in the circuit and is the circuit's resistance.

Solving the equation for , we have

.

We use Ohm's law, , to find the current in the circuit. In Ohm's law is the voltage in the circuit, is the current in the circuit and is the circuit's resistance.

In our problem,

We use Ohm's law, , to find the current in the circuit. In Ohm's law is the voltage in the circuit, is the current in the circuit and is the circuit's resistance.

Solving Ohm's law for resistance gives us

.

A few rules of circuits that will help here for series circuits are:

Method 1:

The current through is given and that will be the same current going through since there are no current junctions. Since the sum of all voltage drops must equal the emf of the battery, the voltage drop across can be found:

We can use Ohm's law to find the resistance:

Method 2:

Ohm's law:

The resistance values are added to get , so

Solve for :

Using ohm's law, the resistance is determined to be which is calculated to be . Ohm's law is used again to find the current at with the same resistance.

To answer this question we need to use the definition of Ohm’s law.

where is voltage, is current, and is resistance. As the equation suggests, to determine the effect of voltage on current we need information regarding the resistance. For example, increasing the voltage will increase the current if resistance decreases or if resistance stays the same. On the other hand, increasing the voltage will decrease the current if the resistance increases drastically; therefore, we cannot determine the effect of voltage on current without knowing anything about the resistance (we need to know if resistance increases, decreases, or stays the same). Similarly, we cannot determine the effect of resistance on the current without knowing about the voltage.