AP Physics 1 Exam Question: Ohm's Law

Question:

A circuit is constructed using a 12-volt battery, a resistor with resistance 6 ohms, and a switch. When the switch is closed, a current of 2 amperes flows through the circuit.

1. Calculate the potential difference across the resistor.

2. If the resistance of the resistor is increased to 12 ohms and the switch is closed again, what will be the new current flowing through the circuit?

Answer:

1. To calculate the potential difference across the resistor, we can use Ohm's Law, which states that the potential difference (V) across a resistor is equal to the current (I) passing through it, multiplied by the resistance (R):

   V = I * R

   Given that the current (I) passing through the resistor is 2 amperes and the resistance (R) is 6 ohms, we can substitute these values into the formula:

   V = 2 A * 6 Ω = 12 V

   Therefore, the potential difference across the resistor is 12 volts.

2. If the resistance of the resistor is increased to 12 ohms, we need to determine the new current flowing through the circuit. Again, we can use Ohm's Law to solve for the current:

   V = I * R

   We know that the potential difference (V) across the resistor is still 12 volts (given by the battery), and the resistance (R) increased to 12 ohms. Rearranging the formula to solve for current:

   I = V / R

   Substituting the values:

   I = 12 V / 12 Ω = 1 A

   Therefore, the new current flowing through the circuit is 1 ampere.

Therefore, the answers to the questions are:

1. The potential difference across the resistor is 12 volts.
2. The new current flowing through the circuit is 1 ampere.