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The number density of free electrons in ...

The number density of free electrons in a copper conductor estimated in Example 3.1 is `8.5 xx 10^(28) m^(-3)`. How long does an electron take to drift from one end of a wire 3.0 m long to its other end? The area of cross-section of the wire is `2.0 xx 10^(-6) m^(2)` and it is carrying a current of 3.0 A.

A

`2.73xx10^(4)s`

B

`4.73xx10^(4)s`

C

`5xx10^(4)s`

D

`6xx10^(8)s`

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The correct Answer is:
A
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The number density of free electrons in a copper conductor is estimated at 8.5 xx 10^(28) m^(-3) . How long does an electron take to drift from one end of a wire 3.0 m long to its other end? The area of cross-section of the wire is 2.0 xx 10^(-6)m^(2) and it is carrying a current of 3.0A.

A uniform copper wire of length 1m and cross section area 5 xx 10^(-7)m^(2) carries a current of 1A . Assuming that are 8 xx 10^(28) free electron per m^(3) in copper, how long will an electron take to drift from one end of the wire an electron the other. Charge on an electron = 1.6 xx 10^(-19)C

Find the average drift speed of free electrons in a copper wire of area of cross-section 10^(-7) m^(2) carrying current of 1.5 A and having free electron density 8.5 xx 10^(28) m^(-3)

Find the average drift speed of free electrons in a copper wire of area of cross-section 10^(-7) m^(2) carrying current of 1.5 A and having free electron density 8.5 xx 10^(28) m^(-3)

In a metal in the solid state, such as a copper wire, the atoms are strongly bound to one another and occupý fixed positions. Some electrons (called the conductor electrons) are free to move in the body of the metal while the other are strongly bound to their atoms. In good conductors, the number of free electrons is very large of the order of 10^(28) electrons per cubic metre in copper. The free electrons are in random motion and keep colliding with atoms. At room temperature, they move with velocities of the order of 10^5 m/s. These velocities are completely random and there is not net flow of charge in any directions. If a potential difference is maintained between the ends of the metal wire (by connecting it across a battery), an electric field is set up which accelerates the free electrons: These accelerated electrons frequently collide with the atoms of the conductor, as a result, they acquire a constant speed called the drift speed which is given by V_e = 1/enA where I = current in the conductor due to drifting electrons, e = charge of electron, n = number of free electrons per unit volume of the conductor and A = area of cross-section of the conductor. A uniform wire of length 2.0 m and cross-sectional area 10^(-7) m^(2) carries a current of 1.6 A. If there are 10^(28) free electrons per m in copper, the drift speed of electrons in copper is

A straight copper-wire of length 100m and cross-sectional area 1.0mm^(2) carries a current 4.5A . Assuming that one free electron corresponds to each copper atom, find (a) The time it takes an electron to displace from one end of the wire to the other. (b) The sum of electrostatic forces acting on all free electrons in the given wire. Given resistivity of copper is 1.72xx10^(-8)Omega-m and density of copper is 8.96g//cm^(3) .

Calculate the electric current density in a uniform wire connected to a battery of emf 3.5 V and negligible internal resistance. The resistance of the wire is 2.0 Omega and its area of cross-section is 0.70 xx 10^(-6)m^(2).

(a) A wire 4 m long and 0.3 mm, calculate the potential energy stored in the wire. Young's modulus for the material of wire is 2.0xx10^(11) N//m^(2) .

An electric current of 16 A exists in a metal wire of cross section 10^(-6) m^(2) and length 1 m. Assuming one free electron per atom. The drift speed of the free electrons in the wire will be (Density of metal = 5 xx 10^(3) kg//m^(3) atomic weight = 60)

Estimate the average drift speed of conduction electrons in a copper wire of cross-sectional area 2.0 xx 10^(-7)m^(2) carrying a current of 3.0 A. Assume that each copper atom contributes roughly one conduction electron. The density of copper is 9.0 xx10^(3) kg//m^(3) , and its atomic mass is 63.5 u.

DC PANDEY ENGLISH-CURRENT ELECTRICITY-Check point
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