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प्रश्न
(a) drift speed
(b) current density
(c) electric current
(d) electric field
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उत्तर
The electric current will remain constant in a wire whose cross-sectional area is increasing linearly from its one end to the other, is connected across a battery of V volts.
Because current is the only quantity that does not depend on the area of cross- sections of the wire.
`I=(dq)/(dt)`, that is the rate of flow of charge, where as drift speed, current density and electric field are depends on the increasing area of cross-section with the following relations:
Drift speed: `ν_d=I/(An""e)`
Current density = `I/A`
Electric field = `J/σ`
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संबंधित प्रश्न
Define the term drift velocity.
Write its (‘mobility’ of charge carriers) S.I. unit
How does drift velocity of electrons in a metallic conductor vary with increase in temperature? Explain.
Derive an expression for drift velocity of free electrons in a conductor in terms of relaxation time.
Electrons are emitted by a hot filament and are accelerated by an electric field, as shown in the figure. The two stops at the left ensure that the electron beam has a uniform cross-section.
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 relaxation time τ is nearly independent of applied E field whereas it changes significantly with temperature T. First fact is (in part) responsible for Ohm’s law whereas the second fact leads to variation of ρ with temperature. Elaborate why?
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.
