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प्रश्न
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.
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उत्तर
We know,
Drift velocity, `v_d = (eE)/mtau ⇒ (eV)/(mL)tau`
Current density, J = `I/A`
If another conductor of the same length will be connected in series. I will remain the same and my potential will become half. So, drift velocity will become half and current density will remain the same.
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संबंधित प्रश्न
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Derive an expression for drift velocity of free electrons in a conductor in terms of relaxation time.
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(A) Free-electron density is different in different metals.
(B) Free-electron density in a metal depends on temperature.
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(A) Free-electron density is different in different metals.
(B) Free-electron density in a metal depends on temperature.
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When a current I is set up in a wire of radius r, the drift velocity is vd· If the same current is set up through a wire of radius 2 r, the drift velocity will be:
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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.
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.
