### All AP Physics 1 Resources

## Example Questions

### Example Question #1 : Ohm's Law

Consider the circuit:

If each resistor has a value of , how much current is flowing through the circuit?

**Possible Answers:**

**Correct answer:**

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:

### Example Question #1 : Ohm's Law

A light bulb requires 60 W to function properly. If it is connected to a powersupply of 120 A and functions properly, then what is the resitance of the light bulb?

**Possible Answers:**

**Correct answer:**

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:

### Example Question #1 : Circuits

What is the resistance of a resistor if the current going through it is and the voltage across it it is ?

**Possible Answers:**

**Correct answer:**

Use Ohm's law.

Plug in known values and solve for resistance.

### Example Question #1 : Circuits

What is the voltage across a resistor with a resistance of that has a current of going through it?

**Possible Answers:**

**Correct answer:**

Use Ohm's Law.

### Example Question #1 : Ohm's Law

What is the current through a resistor if the resistor has a resistance of and the voltage across the resistor is ?

**Possible Answers:**

**Correct answer:**

Use Ohm's law.

### Example Question #1 : Ohm's Law

If the current through a resistor is , what is the voltage across the resistor?

**Possible Answers:**

**Correct answer:**

UseOhm's law.

Plug in known values and solve.

### Example Question #1 : Ohm's Law

The voltage measured from a point between and to the ground is

What is the resistance of ?

**Possible Answers:**

**Correct answer:**

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:

### Example Question #1 : Ohm's Law

, and the voltage measured from a point between and to the ground is

In the circuit above, what is the resistance of ?

**Possible Answers:**

**Correct answer:**

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:

### Example Question #2 : Circuits

is composted of two resistors in parallel, and

is a single resistor.

In the circuit above, what is the current?

**Possible Answers:**

**Correct answer:**

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.

### Example Question #111 : Electricity And Waves

A resistor with a resistance of has a current flowing through it of 5A. What is the potential drop across the resistor?

**Possible Answers:**

**Correct answer:**

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.

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