AP Physics 1 : Understanding Circuit Diagrams

Study concepts, example questions & explanations for AP Physics 1

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Example Questions

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Example Question #161 : Electricity And Waves

Circuit diagram2

In the circuit above, what is the current passing through ?

Possible Answers:

Correct answer:

Explanation:

Find the total resistance of the circuit. First, calculate the values of the combined resistances of the resistors in parallel:

Therefore, the total resistance is:

From Ohm's law, we know that  is the current traveling through the circuit.

This current will be divided between  and , with more current taking the path of lower resistance. 

Total voltage drop across :

The current through  is given by:

Example Question #162 : Electricity And Waves

Circuitdiagram3

In the circuit above, what is the total resistance?

Possible Answers:

Correct answer:

Explanation:

Begin by combining the resistors that are immediately in series:

Circuit diagramab

Now to find the total resistance, combine these two new resistance values, which are in parallel:

Example Question #163 : Electricity And Waves

Circuitdiagram3

In the circuit above, what is the voltage drop across ?

Possible Answers:

Correct answer:

Explanation:

To approach this problem, note that there are no other resistors (or combinations or resistors) beyond the parallel arrangement shown, so the voltage drop across the top  and the bottom  is the same and equal to the voltage across the circuit, .

The voltage drop across  can be found as:

Example Question #164 : Electricity And Waves

Circuitdiagram3

In the circuit above, what is the current passing through ?

Possible Answers:

Correct answer:

Explanation:

To approach this problem, note that there are no other resistors (or combinations or resistors) beyond the parallel arrangement shown, so the voltage drop across the top  and the bottom  is the same and equal to the voltage across the circuit, .

Furthermore, the current that passes through  must be the same as the current that passes through .

Therefore, the current that passes through them can be found by rearranging Ohm's law, solving for current.

Example Question #1321 : Ap Physics 1

Basic circuit2

In the circuit above:

What is the current across ?

Possible Answers:

Correct answer:

Explanation:

The quickest way to approach this problem is to realize that the voltage drop across  is the same as the voltage drop across the combined resistances of  and . Since this parallel combination is the only presence of resistance in the circuit, this voltage drop must be the total voltage of the circuit, .

Therefore, the current across  is:

Example Question #11 : Understanding Circuit Diagrams

Basic circuit2

In the circuit above:

What is the current across ?

Possible Answers:

Correct answer:

Explanation:

Realize that the voltage drop across the combined resistances of  and  must be equal to the voltage of the circuit, since the parallel combination is the only presence of resistance in the circuit. This voltage drop must be the total voltage of the circuit, .

The current across  and  is the same, and is given as:

Example Question #12 : Understanding Circuit Diagrams

Basic circuit2

In the circuit above:

What is the total current in the circuit before it is encounters the parallel connection?

Possible Answers:

Correct answer:

Explanation:

Begin by finding the resistance of the parallel connection:

The total current is then found using Ohm's law:

Example Question #1321 : Ap Physics 1

The following symbol represents what item in a circuit?

Capacitor

Possible Answers:

Inductor

Battery

Capacitor

Resistor

Correct answer:

Capacitor

Explanation:

The symbol for a capacitor is written as a break in the circuit separated by two parallel lines of equal length as shown below. This loosely resembles the most common type of capacitor, a parallel plate capacitor.

Capacitor

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