For example, a bulb glows as soon as the connection is switched on

The current is established almost instantaneously because an electric field is set up in the electric circuit as soon as it is closed, almost with the speed of light.

This leads to drift of local electron at each point in the circuit.
The establishment of a current does not require individual electrons to move from one end to the other end of the conductor.
Each free electron in the conductor accelerates due to the effect of the electric field until it collides with a positive metal ion and loses its drift velocity.
The electrons go through a continuous collision cycle and successive loosing of drift speed until an average drift speed is obtained.

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CBSE CLASS XII Related Questions

1.
Read the following paragraph and answer the questions that follow.
In an experiment with convex lens of focal length f, the screen is fixed at a distance D from the object. A student slowly moves the lens away from the object towards the screen and finds that she is able to form sharp image of the object for two positions of the lens. The distance between these two positions of the lens is d.

2.
An astronomical telescope consists of two converging lenses. One of them of large aperture and large focal length is called objective lens and the other one, of smaller focal length and smaller aperture is called the eyepiece. It is used to see distant objects which are not seen clearly with naked eyes. The image formed by the objective lens acts as an object for the eyepiece and the final image produced by the eyepiece is magnified.

3.
With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

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4.
The resistance of a metal wire at $ 20^\circ \text{C} $ is $ 1.05 \, \Omega $ and at $ 100^\circ \text{C} $ is $ 1.38 \, \Omega $. Determine the temperature coefficient of resistivity of this metal.

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5.
An electric field $\vec{E}$ is established across the ends of a cylindrical conductor of length L and area of cross-section A. Discuss how electrons attain an average velocity, independent of time. Hence, obtain a relation between current in the conductor and this ‘average velocity’ of electrons.

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6.
Write two advantages of reflecting telescope over refracting telescope.

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It is known that the drift velocity of electrons is only a few mm/s for a current of a few amperes. How is it possible that a current is established almost instantaneously when a circuit is closed?

For example, a bulb glows as soon as the connection is switched on

Related Questions

CBSE CLASS XII Related Questions

3.
With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

4.
The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

6.
Write two advantages of reflecting telescope over refracting telescope.

Similar Physics Concepts

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It is known that the drift velocity of electrons is only a few mm/s for a current of a few amperes. How is it possible that a current is established almost instantaneously when a circuit is closed?

For example, a bulb glows as soon as the connection is switched on

Related Questions

CBSE CLASS XII Related Questions

3.With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

4. The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

6.Write two advantages of reflecting telescope over refracting telescope.

Similar Physics Concepts

Comments

SUBSCRIBE TO OUR NEWS LETTER

3.
With the help of a labelled diagram, explain the principle, construction and working of an a.c. generator.

4.
The resistance of a metal wire at \( 20^\circ \text{C} \) is \( 1.05 \, \Omega \) and at \( 100^\circ \text{C} \) is \( 1.38 \, \Omega \). Determine the temperature coefficient of resistivity of this metal.

6.
Write two advantages of reflecting telescope over refracting telescope.