Physics, 04.11.2019 12:31 lottie2306

Avery long, straight wire carries a current of 19.0 a in the +k direction. an electron 1.9 cm from the center of the wire in the î direction is moving with a speed of 3.23 106 m/s. find the force on the electron when it moves in the following directions. (a) directly away from the wire 0 correct: your answer is correct. n î + 0 correct: your answer is correct. n ĵ + n k (b) parallel to the wire in the direction of the current n î + 0 correct: your answer is correct. n ĵ + 0 correct: your answer is correct. n k (c) perpendicular to the wire and tangent to a circle around the wire in the + ĵ direction 0 correct: your answer is correct. n î + 0 correct: your answer is correct. n ĵ + n k

Answers: 2

Show answers

Answers

Answer from: domiyisthom

(a) $1.03\cdot 10^{-16} N$ , -k direction

First of all, let's find the magnetic field produced by the wire at the location of the electron:

$B=\frac{\mu_0 I}{2 \pi r}$

where

I = 19.0 A is the current in the wire

r = 1.9 cm = 0.019 m is the distance of the electron from the wire

Substituting,

$B=\frac{(1.256\cdot 10^{-6})(19.0A)}{2 \pi (0.019 m)}=2\cdot 10^{-4} T$

and the direction is +j direction (tangent to a circle around the wire)

Now we can find the force on the electron by using:

$F=qvBsin \theta$

where

$q=1.6\cdot 10^{-19}C$ is the electron's charge

$v=3.23\cdot 10^6 m/s$ is the electron speed

$B=2\cdot 10^{-4} T$ is the magnetic field

$\theta$ is the angle between the direction of v and B

In this case, the electron is travelling away from the wire, while the magnetic field lines (B) form circular paths around the wire: this means that v and B are perpendicular, so $\theta=90^{\circ}, sin \theta=1$ . So, the force on the electron is

$F=(1.6\cdot 10^{-19}C)(3.23\cdot 10^6 m/s)(2\cdot 10^{-4} T)(1)=1.03\cdot 10^{-16} N$

The direction is given by the right hand rule:

- Index finger: direction of motion of the electron, +i direction (away from the wire)

- Middle finger: direction of magnetic field, +j direction (tangent to a circle around the wire)

- Thumb: direction of the force --> since the charge is negative, the sign must be reversed, so it means -k direction (anti-parallel to the current in the wire)

(b) $1.03\cdot 10^{-16} N$ , +i direction

The calculation of the magnetic field and of the force on the electron are exactly identical as before. The only thing that changes this time is the direction of the force. In fact we have:

- Index finger: direction of motion of the electron, +k direction (parallel to the current in the wire)

- Middle finger: direction of magnetic field, +j direction (tangent to a circle around the wire)

- Thumb: direction of the force --> since the charge is negative, the sign must be reversed, so it means +i direction (away from the wire)

In this case, the electron is moving tangent to a circle around the wire, in the +j direction. But this is exactly the same direction of the magnetic field: this means that v and B are parallel, so $\theta=0, sin \theta=0$ , therefore the force on the electron is zero.

Answer from: Quest

c. magnitude and direction

Answer from: Quest

it is b. absorbs thermal energy

Other questions on the subject: Physics

Physics, 22.06.2019 05:20, niescarlosj

A3.9 g aluminum foil ball with a charge of +4.1×10−9 c is suspended on a string in a uniform horizontal e⃗ field. the string deviates to the right and makes an angle of 30∘ with the vertical. part a part complete what information about the e⃗ field can you determine for this situation? what information about the field can you determine for this situation? only the magnitude of e⃗ only the direction of e⃗ both the magnitude and the direction of e⃗ none of the above previous answers correct part b determine the magnitude of the electric field. express your answer with the appropriate units. e e = nothing nothing request answer part c determine the direction of the electric field. determine the direction of the electric field. to the right to the left away from you toward you

Answers: 3

continue

Physics, 22.06.2019 07:00, jeremiahphillip4396

The speed of sound in ice, water, and steam is shown. what best explains the speed of sound in different states of matter? sound travels fastest in ice because energy is easier to transfer when the molecules are close together. sound travels slowest in steam because the sound has to move around the gas molecules that are far apart. sound travels fastest in ice because the temperature of solids is always greater, so the heat transfers the sound energy. sound travels slowest in steam because the pressure is so great the sound cannot travel though the steam particles.

Answers: 1

continue

Physics, 22.06.2019 12:30, gracedaniels68

What’s #16 asking me and how do i solve it?

Answers: 2

continue

Physics, 22.06.2019 15:00, sloane50

What happens to an isotope during radioactive decay?

Answers: 2

continue

You know the right answer?

Avery long, straight wire carries a current of 19.0 a in the +k direction. an electron 1.9 cm from t...