Resistors

Help Questions

Physics › Resistors

Questions 1 - 10

Screen shot 2020 08 24 at 8.50.00 am

Which Resistors are connected in parallel?

All answer choices are correct

$R_{1}$ and $R_{2}$

$R_{2}$ and $R_{3}$

$R_{1}$ and $R_{3}$

None of the answer choices are correct

Explanation

Resistors are in parallel when the electric current passes through two or more branches or connected parts at the same time before it combines again. After the current leaves the battery it travels to $R_{2}$ . Then the current splits and travels between the other two resistors before the current coming back together and connecting back to the battery.

The resistivity of most common metals __________________ .

remains constant over wide temperature ranges

increases as the temperature increases

decreases as the temperature increases

varies randomly as the temperature increases

Explanation

At higher temperature, the atoms are moving more rapidly and are arranged in a less orderly way. Therefore it is expected that these fast moving atoms are more likely to interfere with the flow of electrons. If there is more interference in the flow of electrons, then there is a higher resistivity.

Screen shot 2020 08 24 at 8.50.00 am

Which Resistors are connected in parallel?

All answer choices are correct

$R_{1}$ and $R_{2}$

$R_{2}$ and $R_{3}$

$R_{1}$ and $R_{3}$

None of the answer choices are correct

Explanation

The resistivity of most common metals __________________ .

remains constant over wide temperature ranges

increases as the temperature increases

decreases as the temperature increases

varies randomly as the temperature increases

Explanation

Screen shot 2020 08 24 at 8.54.25 am

Which resistor has the greatest current going through it?

Assume all the resistors are equal.

$R_{1}$

$R_{1}$ and $R_{2}$

$R_{3}$ and $R_{4}$

$R_{5}$

Explanation

As we examine the circuit we first come across the first two resistors. These resistors are in parallel. In parallel circuits, the current splits to go down each branch. In this case, the resistors are of equal value meaning that the current is split evenly between the two.

We then come across another parallel branch with two resistors on one side and a single resistor on the other side. The two resistors in series add up to create more resistance on the top branch. The single resistor on its own has less resistance.

Since current always chooses the path of least resistance, more current will flow through the single resistor, than through the branch with two resistors in series.

Therefore, would have the greatest resistance flowing through it.

What is the diameter of a length of tungsten wire whose resistance is ohms?

Explanation

We will use the resistivity equation to solve for this. We know

Length =

Resistance =

ρ of Tungsten = $5.6x10^-8 \Omega m$

The equation for resistivity is

$R = \rho \frac{L}{A}$

We can rearrange this equation to solve for

$A =\rho \frac{R}{L}$

In this case the area of the wire is the area of a circle which is equal to $\pi r^2$

We can rearrange this to get the radius by itself

$r = \sqrt{\frac{\rho R}{L \pi}}$

$r = \sqrt{\frac{(5.6x10^-8)(0.32)}{(1)(\pi)}}$

To find the diameter we need to multiply this value by 2.

Screen shot 2020 08 24 at 8.54.25 am

Which resistor has the greatest current going through it?

Assume all the resistors are equal.

$R_{1}$

$R_{1}$ and $R_{2}$

$R_{3}$ and $R_{4}$

$R_{5}$

Explanation

Since current always chooses the path of least resistance, more current will flow through the single resistor, than through the branch with two resistors in series.

Therefore, would have the greatest resistance flowing through it.

What is the diameter of a length of tungsten wire whose resistance is ohms?