sir can you please explain me what is drift speed...
Asked by Megha | 23rd Jun, 2014, 09:03: PM
A conductor contains large number of loosely bound electrons called free electrons or conduction electrons and the remaining material is a collection of relatively heavy positive ions called lattice.The free electrons in a conductor are always in random motion .This random motion is due to the thermal energy of the conductor. The velocity of a free electron due to thermal energy of the conductor is called thermal velocity and is very large.
The number of free electrons in a conductor is very large and due to their random motion they keep on colliding with the positive ions in the cionductor,The collision is so frequent that the net flow of electrons in any particular direction is zero.
However when some potentiial difference is applied across the two ends of a conductor, an electric field is set up.If 'V' is the potential difference applied and 'l ' the length of the conductor, then the magnitude of electric field set up , E =V / l.
When there is an electric filed inside the conductor , a force acts on each electron in the direction opposite to the field.The electrons get biased in their random motion in favour of the force.As a result the electrons drift slowly in this direction.At each collision electrons start afresh in a random direction with a random speed but gains an additional velocity due to the electric field. This velocity increses with time and suddently becomes zero as the electrons makes a collision with the lattice and starts afresh with a random velocity. As the time 't' between successive collisions is small, the electrons slowly and steadily drifts opposite to the applied field. If the electrons drift a distance 'l' in a long time 't' we can define drift speed as
And the short time for which a free electron accelerates before it undergoes a collision with the positive ion in the conductor , is called relaxation time.
The average velocity with which free electrons in a conductor gets drifted under the influence of an external electric field applied across the conductor is called drift velocity.
Answered by Jyothi Nair | 24th Jun, 2014, 09:43: AM
- what is volt
- why does need to maintain the current in a given electric circuit by expanding its energy stored in it?
- The flow of electrons is opposite to the direction of the flow of current as electron is negatively charged . Then why current is defined as the flow of electrons through the conductor though current travels from positive to negative terminal.
- If charge on one electron is 1.6 x 10 -19 C. Calculate number of electrons required to constitute 1A of current in 1s.
- what is the power of torch bulb rated at 2.5V and 500 mA?
- The MCB of a Rupa’s room is tripped and keeps on tripping again and again. If it is a domestic circuit, what could be the reason of this phenomenon?
- a current
- if 20 C of charge pass a point in a circuit in 1 second what current is flowing
- an electric bulb is related220 V and 100 W when it is operated on 110 V the power consumed will be
- A coil draws a current of 1.0 ampere and a power of 100 watt from an A.C. source of 110 volt and 5√22/π hertz. Find the inductance and resistance of the coil. Why can't I use P=VI here, and how can I determine when to use P=VI or P=I^2 R or P=V^2 / R
Kindly Sign up for a personalised experience
- Ask Study Doubts
- Sample Papers
- Past Year Papers
- Textbook Solutions
Verify mobile number
Enter the OTP sent to your number