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3 years ago

When electrons move back and forth, reversing their direction regularly, the current is called?

1 answer:

4 0

It is called "alternating current" or "ac current".

An alternating current is a current the periodically changes direction. Basically, the voltage difference applied at the two ends of the wire / of the circuit is constantly reversed. This means that at some point electrons travel in one direction, then the voltage is switched (i.e. the polarities are exchanged) and the electrons start to flow into the opposite direction, and so on.

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The container contains

monitta

What is the question

7 0

2 years ago

A girl (mass M) standing on the edge of a frictionless merry-go-round (radius R, rotational inertia I) that is not moving. She t

vladimir1956 [14]

a) $\omega=\frac{-mvR}{I+MR^2}$

b) $v=\frac{-mvR^2}{I+MR^2}$

Explanation:

Since there are no external torques acting on the system, the total angular momentum must remain constant.

At the beginning, the merry-go-round and the girl are at rest, so the initial angular momentum is zero:

$L_1=0$

Later, after the girl throws the rock, the angular momentum will be:

$L_2=(I_M+I_g)\omega +L_r$

where:

$I$ is the moment of inertia of the merry-go-round

$I_g=MR^2$ is the moment of inertia of the girl, where

M is the mass of the girl

R is the distance of the girl from the axis of rotation

$\omega$ is the angular speed of the merry-go-round and the girl

$L_r=mvR$ is the angular momentum of the rock, where

m is the mass of the rock

v is its velocity

Since the total angular momentum is conserved,

$L_1=L_2$

So we find:

$0=(I+I_g)\omega +mvR\\\omega=\frac{-mvR}{I+MR^2}$

And the negative sign indicates that the disk rotates in the direction opposite to the motion of the rock.

The linear speed of a body in rotational motion is given by

$v=\omega r$

where

$\omega$ is the angular speed

r is the distance of the body from the axis of rotation

In this problem, for the girl, we have:

$\omega=\frac{-mvR}{I+MR^2}$ is the angular speed

$r=R$ is the distance of the girl from the axis of rotation

Therefore, her linear speed is:

$v=\omega R=\frac{-mvR^2}{I+MR^2}$

5 0

3 years ago

The mere exposure effect is

gulaghasi [49]

DescriptionThe mere-exposure effect is a psychological phenomenon by which people tend to develop a preference for things merely because they are familiar with them.

6 0

3 years ago

A car accelerates from 10 km/hr to 50 km/hr in 8 seconds. What is the acceleration?

nikklg [1K]

The answer is 5 km/hr