The cause of electric current in a wire is that there is electron flow due to electrical attraction and repulsion.
What is Electric current?
The rate of flow of electric charge through a point is known as electric current. The electric current is nothing but the flow of electrons in general.
Consider a space, when electrons of charge (e) is flowing through the space in a given time interval t. Then,
I = e/t
here,
I is the electric current.
Moreover, there is a flow of electrons in a wire due to a potential difference existing at the circuit. Due to that, electrons always flow from high electric potential to low electric potential.
Thus, we can conclude that the cause of electric current in a wire is that there is electron flow due to electrical attraction and repulsion.
Learn more about the electric current here:
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Answer:
student A or B
Explanation:
A common demonstration is to put a ringing alarm clock or bell in the bell jar, and when the vacuum is created, you can no longer hear the sound of the clock/bell.
The bell is connected to a lab pack or batteries and rung to show pupils it can be heard under normal circumstances. The bell jar is then connected to a vacuum pump using a vacuum plate (see Fig 2) and the air is removed from inside creating a near vacuum. The bell is then again rung. This time however, it cannot be heard.
Small low voltage buzzers can be used as a bell replacement for the bell and work in exactly the same way though teachers generally prefer bells as students may be able to see the hammer moving, proving that it is actually ringing even though they cannot hear it.
Some vacuum pumps are better than others at keeping a strong vacuum though if you cannot completely lose the sound, you will at least notice the volume decreasing.
Sound is simply a series of longitudinal waves travelling from the source, through the air to our ears. Without air present, these waves cannot form and therefore sound cannot be conveyed.
In a longitudinal wave the particles oscillate back and forth in the direction of the wave movement unlike transverse waves which like waves on the sea, single particles travel up and down and not in the direction of the wave.
Because you will not be able to create a perfect vacuum, you may still be able to hear the bell ring slightly. Vibrations from the ringing bell can also travel up to the bung in the bell jar which in turn may resonate the jar slightly. This means you may hear the bell ring, however strong the vacuum. To compensate for this, try to insulate the bell as much as possible from the bell jar. Hanging the bell using elastic cord means some of the vibrations will be absorbed by the cord and not be transferred to the bell jar.
Answer:
The position is 8.18cm from the mirror.
Nature is b=virtual
Size is 1.82cm
Explanation:
Note that for a convex mirror, the image distance and the focal length are negative;
Given
Object height H0 = 4cm
object distance u = 18cm
Radius of curvature R = 30cm
Since f = R/2
f = 30/2
f = -15cm
Recall that:
Since the image distance is negative, this shows that the image is a virtual image.
To get the size:
Answer:
But if you place a clear container filled with hydrogen gas between the flashlight and the prism, gaps appear in the smooth rainbow of colors, places where the light literally goes missing. The dark absorption lines of a star at rest (left) get shifted towards red if the star is moving away from Earth (right)
Explanation:
Conduction is slower in liquids and gases.
Liquids it is convection which transmits more heat.. quicker...
Materials which are good conductors of thermal energy are called thermal conductors.
metals are good thermal conductors.
