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The number of free electrons is Si at no...

The number of free electrons is Si at normal temperature is

A

`2.5xx10^(6) "per cm"^(3)`

B

`1.5xx10^(10) "per cm"^(3)`

C

`1.5xx10^(13) "per cm"^(3)`

D

`2.5xx10^(13) "per cm"^(3)`

Text Solution

Verified by Experts

The correct Answer is:
B
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A cylindrical copper conductor AB length L areaa of cross-section a has large number of free electrons which at mean temperature move at random within the body of the conductor like the molecules of a gas. The average thermal motion at room temperature is of the enter of 10^(5)ms^(-1) where a potential difference V is applied free electronic in the condictior experience , the free electrons in the conductor experience force and are accelerated towards the positive emf of the condutor on their gained kinetic energy After each collision the free electronic are angle acceleration due of the electric field , towards the positive end the conductor and next collision with the ions/atoms of the electrons The average speed of the free electrons with which they drift toward the positive and of the conductor under the effect of applied electric field is called drift of the electrons When the potential difference is applied the two ends of the conductors , an electric field exists

In a semiconductor, (i)there are no free elctrons at 0K (ii) there are no free elctrons at any tempreture (iii) the number of free electrons increases with tempreture (iv) the number of free electrons is less than that in a conductor

Knowledge Check

  • A cylindrical copper conductor AB length L areaa of cross-section a has large number of free electrons which at mean temperature move at random within the body of the conductor like the molecules of a gas. The average thermal motion at room temperature is of the enter of 10^(5)ms^(-1) where a potential difference V is applied free electronic in the condictior experience , the free electrons in the conductor experience force and are accelerated towards the positive emf of the condutor on their gained kinetic energy After each collision the free electronic are angle acceleration due of the electric field , towards the positive end the conductor and next collision with the ions/atoms of the electrons The average speed of the free electrons with which they drift toward the positive and of the conductor under the effect of applied electric field is called drift of the electrons The drift speed of the electrons depends on

    A
    dimension of the conductor
    B
    number density of free electrons in the conductor
    C
    both (a) and (b)
    D
    none of these above

  • A cylindrical copper conductor AB length L areaa of cross-section a has large number of free electrons which at mean temperature move at random within the body of the conductor like the molecules of a gas. The average thermal motion at room temperature is of the enter of 10^(5)ms^(-1) where a potential difference V is applied free electronic in the condictior experience , the free electrons in the conductor experience force and are accelerated towards the positive emf of the condutor on their gained kinetic energy After each collision the free electronic are angle acceleration due of the electric field , towards the positive end the conductor and next collision with the ions/atoms of the electrons The average speed of the free electrons with which they drift toward the positive and of the conductor under the effect of applied electric field is called drift of the electrons The motion of electrons in between two successive collisions with the atoms/ions follows

    A
    a straight path
    B
    circular path
    C
    elliptical path
    D
    curved path

  • A cylindrical copper conductor AB length L areaa of cross-section a has large number of free electrons which at mean temperature move at random within the body of the conductor like the molecules of a gas. The average thermal motion at room temperature is of the enter of 10^(5)ms^(-1) where a potential difference V is applied free electronic in the condictior experience , the free electrons in the conductor experience force and are accelerated towards the positive emf of the condutor on their gained kinetic energy After each collision the free electronic are angle acceleration due of the electric field , towards the positive end the conductor and next collision with the ions/atoms of the electrons The average speed of the free electrons with which they drift toward the positive and of the conductor under the effect of applied electric field is called drift of the electrons The speed of electrons in a conductor is small (= 10^(-4) ms^(-1)) when the switch is closed, the bulb at a distance glows immediately. It is so because

    A
    drift velocity of electrons increase when swich in closed
    B
    electrons are accelerated towards the position end of the conductor and their velocity increase toward the other end of the conductor
    C
    the drifting of electrons takes place at the enter length of the connecting wire This electrics effective propagates with the speed of light
    D
    the electrons towards the position end and protons of condictor move toward negative end of the conductor

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