Physics - Use Ohm's Law

What is the voltage of a circuit with of current and $20\Omega$ of resistance?

Explanation

For this problem, use Ohm's law: . In this equation is the voltage, is the current, and is the resistance.

Plug in the given values and solve for the voltage.

$V=10A*20\Omega$

The current in a circuit is and the voltage is . What is the resistance?

$2.86: \Omega$

$0.35: \Omega$

$3500: \Omega$

$135: \Omega$

Explanation

Ohm's law says . Plug in our given values to solve.

$\frac{100V}{35A}=R$

$2.86\Omega=R$

What is the current of a circuit with a voltage of and a total resistance of $5\Omega$ ?

Explanation

For this problem, use Ohm's law: . In this equation is the voltage, is the current, and is the resistance.

We can re-arrange the equation to solve specifically for .

Plug in the given values for voltage and resistance to solve for the current.

$12V/5\Omega =I$

A circuit has a current, , a voltage, , and a resistance, . If the voltage remains constant, but the current is doubled (), what must the new resistance be?

$\frac{1}{2}R$

$\frac{1}{4}R$

There is insufficient information to solve

Explanation

To solve this problem, use Ohm's law:

Since we are doubling the current, but the voltage is remaining the same, we can set our old and new equations equal to each other.

We know that the second current is equal to twice the first current.

Use this equation to substitute current into the first equation.

The initial current now cancels out from both sides.

Divide both sides by two to isolate the final resistance variable.

$\frac{1}{2}R_1=R_2$

What is the resistance in a circuit with a voltage of and a current of ?

$400\Omega$

$6.25\Omega$

$58\Omega$

$0.16\Omega$

$42\Omega$

Explanation

For this problem, use Ohm's law: . In this equation is the voltage, is the current, and is the resistance.

We can re-arrange the equation to solve specifically for .

Plug in the given values for voltage and current and solve for resistance.

$6.25\Omega =R$

A circuit has a current, , a voltage, , and a resistance, . If the voltage remains constant, but the current is doubled (), what must the new resistance be?