Podcast
Questions and Answers
What is necessary for a net flow of charges in a conductor?
What is necessary for a net flow of charges in a conductor?
- An electric potential applied across the conductor (correct)
- A large number of positively charged particles
- A magnetic field present around the conductor
- A high temperature environment
What do the negatively charged electrons leave behind when they move through a conductor?
What do the negatively charged electrons leave behind when they move through a conductor?
- A positively charged hole (correct)
- A negative ion
- A neutral particle
- Another electron
What does the term 'drift velocity' refer to in the context of electric current?
What does the term 'drift velocity' refer to in the context of electric current?
- The speed of electrons in vacuum
- The maximum speed of electric potential
- The average speed at which charged particles flow (correct)
- The speed at which thermal energy is transferred
In the expression $dI = nA v_d e$, what does the variable 'n' represent?
In the expression $dI = nA v_d e$, what does the variable 'n' represent?
Which of the following represents current density in a conductor?
Which of the following represents current density in a conductor?
Flashcards
What is the role of electric potential in current flow?
What is the role of electric potential in current flow?
In a conductor, free electrons move randomly with no net flow of charge. To create current, an electric potential needs to be applied, causing electrons to drift in a specific direction.
What is drift velocity?
What is drift velocity?
The average velocity at which electrons move in a conductor under the influence of an electric field.
How is charge density defined?
How is charge density defined?
The quantity of charge flowing per unit volume of a conductor.
Define electric current.
Define electric current.
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What is current density?
What is current density?
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Study Notes
Electric Current
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Conductors contain free electrons, but without an electric field, their random motion cancels out, resulting in no net charge flow.
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Applying a voltage creates an electric field.
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This field directs negatively charged electrons in the opposite direction of the field.
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Electrons moving through a conductor create a measurable current.
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The direction of electron flow is opposite to the conventional current flow. In conventional current flow, positive charges move from the positive to the negative terminal.
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Drift velocity is the average velocity of charge carriers in the direction of the electric field.
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The quantity of charge flowing per unit time is the electric current.
Electric Current Formula
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dQ = n e dV
• dQ: change in charge • n: number density of charge carriers (electrons) • e: charge of an electron (1.6 x 10-19 C) • dV: change in volume -
dI = dQ/dt (electric current) • dI = n e vd A
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J = I/A (current density) • J = n e vd
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vd: drift velocity
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A: area of the cross-section
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