Advertisements
Advertisements
प्रश्न
Why alloys like constantan and manganin are used for making standard resistors?
Advertisements
उत्तर
Alloys like constantan and manganin are used for making standard resistors because
(a) they have high value of resistivity
(b) temperature cofficient of resistance is less
संबंधित प्रश्न
Define the term drift velocity.
Write its (‘mobility’ of charge carriers) S.I. unit
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 1.8 A. Assume the density of conduction electrons to be 9 × 1028 m−3.
Derive an expression for drift velocity of free electrons in a conductor in terms of relaxation time.
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 _______________ .
The position-time relation of a particle moving along the x-axis is given by x = a - bt + ct2 where a, band c are positive numbers. The velocity-time graph of the particle is ______.
The drift velocity of a free electron inside a conductor 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?
Derive an expression for resistivity of a conductor in terms of the number density of charge carriers in the conductor and relaxation time.
Explain how free electrons in a metal at constant temperature attain an average velocity under the action of an electric field. Hence, obtain an expression for it.
