Q&A

What is the relation for resistivity in terms of n charge density and relaxation time?

What is the relation for resistivity in terms of n charge density and relaxation time?

Consider a conductor having length l, area of cross section A and current density n. Therefore, the expression for electrical resistivity is given by ρ=mne2τ. Note: Electrical resistivity is inversely proportional to relaxation time.

How is the resistivity of metals depends on relaxation time and charge density?

Free electrons collide more frequently with the positive metal ions. The relaxation time decreases. Consequently, the resistivity of the metal increases.

What happens to resistivity when relaxation time increases?

Current Electricity. Write the mathematical relation for the resistivity of a material in terms of relaxation time, number density and mass and charge of charge carriers in it. And, since resistivity has an inverse dependence on relaxation time, resistivity ρ of the metal increases.

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What is relaxation time establish the relation between relaxation and drift velocity?

The drift velocity is just the average velocity of the charge carriers in the conductor. So, as you now see, the drift velocity is proportional to the relaxation time . As the relaxation time increases the drift velocity increases, because the charge carriers have more time to accelerate between collisions.

What is the relation between relaxation time and temperature?

When the temperature of a good conductor decreases, the number of collisions of electrons also decreases. Hence, the time of free travel increases or relaxation time increases. so time of relaxation increases.

Which is the correct relationship between resistance R and relaxation time C?

R= Rho × l/ A.

What is the relation between conductivity and relaxation time?

The conductivity of a material is directly proportional to this relaxation time; highly conductive materials have relatively long relaxation times.

What is the relation with relaxation time?

We can understand from the solution that the mobility and the relaxation time are directly related. When the collision happens after a longer interval, i.e., higher relaxation time, the mobility of the electrons is higher, i.e., they can move smoothly for more distance.

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Does drift velocity depend on relaxation time?

Yes, drift velocity is independent of time. Drift velocity is the reason due to which current flows inside a conductor. In the derivation of the equation of drift velocity, we can see that acceleration “a” is constant and relaxation time “乁” is kept constant. So current and drift velocity does not depend on time.

How does relaxation time vary with temperature class 12?

When the temperature of the conductor increases, the resistivity of the conductor increases and hence according to the formula the relaxation period decreases.

What is the relation between mobility and relaxation time?

Mobility is defined at the velocity of the electron per unit electric field. It is the ease with which the electrons can travel in a conductor. So, the mobility of the electrons is directly proportional to the relaxation time of the electron.

How is resistance dependent on relaxation time?

Hint: As we know that the relaxation time is inversely proportional to the resistance of the metals. The variation of resistance with temperature in metals is directly proportional so when the temperature increases the resistance increases and vice versa.

What is the relation between resistivity relaxation time number density and charge?

Originally Answered: what is the relation between resistivity, relaxation time, number density and charge of charge carriers? Resistivity = m/n.e^2.tau , where m is the mass of electron, n is no. Density, e is the charge on an electron and tau is the relaxation time or mean free time ( time in which charge carriers are free from collisions)

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What is the relationship between temperature and resistivity?

(i) Case of metals: As temperature increases, the thermal speed of electrons increases and consequently, free electrons collide more frequently with the positive metal ions thereby, decreasing the relaxation time τ. And, since resistivity has an inverse dependence on relaxation time, resistivity ρ of the metal increases.

How do you calculate the resistivity of an electron?

Resistivity = m/n.e^2.tau , where m is the mass of electron, n is no. Density, e is the charge on an electron and tau is the relaxation time or mean free time ( time in which charge carriers are free from collisions) Resistivity is mainly due to scattering or collisions. More is mean free time (means less collisions) , means resistivity is small.

What is the effect of temperature on the relaxation time of electrons?

(i) Metals: As the temperature increases, the thermal speed of electrons increases. Free electrons collide more frequently with the positive metal ions. The relaxation time decreases. Consequently, the resistivity of the metal increases. (ii) Semiconductors: The relaxation time does not change with the temperature.

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