All AP Physics 1 Resources
Example Questions
Example Question #2 : Current And Voltage
Consider the circuit:
By how much does the current through the circuit decrease if R3 is removed?
We are asked to compare two different scenarios, each involving the calculation of equivalent resistance, which will use the following formula:
Scenario 1: With R3 Present
Now using Ohm's law:
Scenario 2: Without R3
Now using Ohm's law:
Calculate the change in current:
Example Question #5 : Current And Voltage
Consider the circuit:
How much current is flowing through R1?
Although it is possible to solve this problem by calculating an equivalent resistance, calculating a total current through the circuit, and then using Kirchoff's junction rule to find the current through R1, it is much easier to simply use Kirchoff's Loop rule. What this rule says is that through any closed loop in a circuit, all voltages must add up to zero. Written as an equation:
If we consider the closed loop path consisting of only the power supply and R1, we can use Ohm's law to calculate the current:
Example Question #126 : Electricity
Consider the circuit:
The total current through the circuit is and the current through R2 is . What is the value of R2?
The total current through the circuit is unnecessary to solve this problem. We only need to know the current through the resistor, as well as Kirchoff's loop rule. The loop rule states that for any closed loop through a circuit, the voltages add up to zero.
For this problem, we will consider the loop that consists solely of the voltage source and R2. From the rule, we know that 12V is lost through the resistor. Using Ohm's law, we can write:
Rearranging for R2, we get:
Example Question #2 : Current And Voltage
In this circuit above, and . The voltage drop across is eight volts. What is the current across the circuit?
The voltage drop is related to the current and resistance via Ohm's law:
Example Question #2 : Current And Voltage
A student has created the given circuit diagram. It consists of a battery, a resistor, and a light bulb. In one minute, 1.2C of charge flows through the resistor. How much charge flows through the light bulb in one minute?
Since the bulb and the resistor are connected in series, the current is the same in each. Electric current is just the flow of charge through the circuit, so the same amount of charge flows through each in one minute.
Example Question #5 : Current And Voltage
If a TV uses of energy over the course of , and it has a voltage of , how many coulombs passed through it during that time?
Because the TV uses , and it was used for , it must have used
.
so:
, and since the TV was used for
Example Question #201 : Electricity And Waves
Give the SI units for voltage.
We have to know what SI units are for this problem. SI units are units that cannot be broken down into smaller component parts. Voltage is defined as:
, where is joules and is Coulombs. Coulombs are already in SI units. However, joules is composed of other terms.
Therefore, voltage can be written as
Example Question #132 : Electricity
of charge pass through a television during a movie. How much is being used by the television?
Current and charge are related by the equation where is the current in Amperes (), is the charge in Coulombs (), and is the time in seconds ().
Time must first be converted to seconds.
Solving for current,
Example Question #133 : Electricity
Who long (in hours) does it take a computer to use of charge ?
Current and charge are related by the equation where is the current in Amperes (), is the charge in Coulombs (), and is the time in seconds ().
For this problem
Example Question #134 : Electricity
What quantity of charge passes through a clock in if its current is ?
Current and charge are related by the equation where is the current in Amperes (), is the charge in Coulombs (), and is the time in seconds ().
Time must first be converted to seconds.
Solving for charge,
.
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