# Drift Velocity

1. Mar 28, 2012

### shayaan_musta

Hello experts!

Higher the emf of the battery implies that the higher the drift speed of the electrons or increase the flow time of electrons from the conductor?

Which one is true and how??

2. Mar 28, 2012

### Philip Wood

Higher emf implies higher electric field strength in the wires of the circuit, so greater force on the free electrons urging them through the wires. So they will reach a higher mean drift speed (at which resistive collision forces balance the electric field forces). Can't, I'm afraid, understand your alternative, but I suspect that it's incorrect.

Hope this outline explanation helps.

3. Mar 28, 2012

### shayaan_musta

I mean,
let a battery of 9volt is connected to the toy fan and on the other hand a battery of 1.5volt is connected to the toy fan.

So which fan will move faster?

Will higher emf cause the speed of fan to increase or increase the moving time of the toy fan?

4. Mar 28, 2012

### Philip Wood

The fan will turn faster on the 9V battery (or its motor will burn out!). [Can't see any mention of a fan in your first post...]

5. Mar 29, 2012

### shayaan_musta

But how will you justify this statement from practical point of view?

6. Mar 29, 2012

### Philip Wood

I won't. I'll leave it to cleverer people – those, for example, who can interpret what you mean by 'a practical point of view'.

7. Mar 29, 2012

### shayaan_musta

I mean If someone asks you that on 9volt battery fan move faster than on 1.5volt battery, why? then what will be your answer?

Either more electrons move from 9volt battery to fan than 1.5volt battery or some else reason you would give in justification for your answer?

8. Mar 29, 2012

### Philip Wood

The rate at which electrons flow round the circuit – your "from ... to" is a bit misleading – is increased (for reasons sketched in my first reply on this thread). So a larger current flows through the coils of the motor in the fan, so these (sitting as they are in a magnetic field) experience a greater torque, and the motor runs faster (until this electromagnetic torque is balanced by that from resistive forces).

Is this the sort of explanation you're looking for?

9. Mar 30, 2012

### shayaan_musta

Yeah.. Thanks a lot. Thread is solved now. :)