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प्रश्न
Is the momentum conserved when charge crosses a junction in an electric circuit? Why or why not?
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उत्तर
When an electron approaches a junction, in addition to the uniform E that it normally faces (which keep the drift velocity vd fixed), there are accumulation of charges on the surface of wires at the junction. These produce electric field. These fields alter direction of momentum.
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संबंधित प्रश्न
Derive an expression for drift velocity of free electrons.
What is its relation with relaxation time?
Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area 2·5 × 10−7 m2 carrying a current of 2·7 A. Assume the density of conduction electrons to be 9 × 1028 m−3
Consider the following statements.
(A) Free-electron density is different in different metals.
(B) Free-electron density in a metal depends on temperature.
Seebeck Effect is caused _____________ .
Consider the following statements.
(A) Free-electron density is different in different metals.
(B) Free-electron density in a metal depends on temperature.
Thomson Effect is caused _______________ .
An electric bulb.is rated 220 v and 100 watt power consumed by it when operated on 'no volt is:-
The drift velocity of a free electron inside a conductor is ______
The identical conductors maintained at same temperature are given potential difference in the ratio 1 : 2. Then the ratio of their drift velocities is ______.
The potential difference applied across a given conductor is doubled. How will this affect (i) the mobility of electrons and (ii) the current density in the conductor? Justify your answers.
A potential difference (V) is applied across a conductor of length 'L' and cross-sectional area 'A'.
How will the drift velocity of electrons and the current density be affected if another identical conductor of the same material were connected in series with the first conductor? Justify your answers.
The drift velocity of electrons in a conductor connected to a battery is given by vd = `(−"eE" τ)/"m"`. Here, e is the charge of the electron, E is the electric field, τ is the average time between collisions and m is the mass of the electron.
Based on this, answer the following:
- How does the drift velocity change with a change in the potential difference across the conductor?
- A copper wire of length 'l' is connected to a source. If the copper wire is replaced by another copper wire of the same area of cross-section but of length '4l', how will the drift velocity change? Explain your answer.
What is the average time interval between two successive collisions of a free electron with the ions of the metallic lattice called?
What is current density?
What does conductivity, denoted by \[\sigma\], measure?
What is the net current in a conductor in the absence of an electric field?
Which expression gives the acceleration of an electron in an electric field?
If \[n\] is the number of free electrons per unit volume and \[A\] is the conductor’s cross-sectional area, which expression gives the current from electron drift?
Which expression gives current density in terms of free electron density, relaxation time, and electric field?
What is the effect of collisions on the acceleration produced by an electric field?
