Let us discuss Physics questions - Page 2

[quote]why there is a flow of current( although very small ) when a p-n junction is reverse biased?

On reverse bias, electrons and holes are pulled aways from the junction. This causes transient current to flow. When the potential formed by the depletion layer equals the applied volatage, then there is very small current flow, which is thermal current.

Ab kuch zyaada ho gaya hai

I'll just read n try to understand the questions n answers.

Shall I answer the question I asked? Let me wait for lrllover's reply. If he also feels that I should give the answer, then I will.

No it's ok...Nishant ko Physics aati hai...he'll answer 😊

Originally posted by: amail1601

No it's ok...Nishant ko Physics aati hai...he'll answer 😊

hailaaaa physics and me? 😕 .......thori bahut aati hai mujhe....abhi bahut kuch seekhna baaki hai

bol kabse tution degi tu? 😆 😆

@akhl

the bus moves with respect to ground....that is w.r.t a frame of reference fixed to the ground

now if we consider the bus as the frame of reference or if we take the origin of the frame of reference as the point where the camera is fixed then the objects on the bus are always at rest w.r.t. the camera(if we neglect the motion due to bad roads/bumps extra(India main neglect nahin kar sakte hai 😆 😆 .........

as the bus starts to move w.r.t.GROUND then also the relative seperation between the objects on the bus and the camera remains the same...i.e.objects are at rest w.r.t. the camera......however when the bus starts to move w.r.t the ground reference frame the lower part of the body moves along with the busand so does the camera fixed to the bus and hence the sepertion between the camera and the lower part of the body remains the same however the upper part of the body due to inertia of rest tends to remain at rest W.R.T. ground reference frame for a little while whereas the camera fixed to the bus moves along with the bus(w.r.t ground reference frame) as a result of which in camera's/bus' frame of reference there occurs a little displacement of the upper part of the body in the backward direction

i hope my explanation is clear.....if not then feel free to ask for a more detailed explanation

or if you think that my approach is wrong then you can give the answer......

Ok...ab samajh aa gaya...I said the same thing 😆 😆 Didn't explain properly though 😛

Nishant,
You are right. And amail1601 (dont' know your name), if you also said the same thing, then you are also right. 😊

Nishant,
The reason I posted this question is because often people say that the bus moves and they use inertia to explain why the passenger should fall backward. But, in camera's frame of reference, the bus never moves.

Your explanation is correct. You have used two frames of reference (ground and camera). There is another explanation, which requires the frame of reference to be put only on the camera.
Camera is tied to the bus. So, camera's frame is the same as the bus's frame. When driver starts the bus, then tyres rotate. Tyres push ground in the backward direction. By Newton's 3rd law, ground pushes tyres and thus the bus in the forward direction. This is force of friction. Bus moves because of this force of friction. Since there is a net external force on the bus, the bus's frame of reference is non-inertial and hence camera's frame is also non-inertial. The acceleration of this frame is in the forward direction.
When we study a system in non-inertial frame, then together with real forces, we should also consider pseudo force. The pseudo force is in the opposite direction of the direction of the frame's acceleration.
In our problem, system is passenger, frame of reference is on the camera (or we can also say, on the bus), frame's acceleration is in the forward direction. So, the pseudo force on the passenger is in the backward direction. Because of this pseudo force, the passenger falls backward.
The pseudo force acts on the lower portion of the passenger's body also. But this part does not move because when it tries to move, then the friction between the seat and the passenger body prevents the lower part of the body to move. If the seat is very smooth, then even the lower part will move somewhat.

What about the question you asked - regarding pn junction? Is thermal current correct answer?

@akhl(dunno your name)...You can call me Ammu.

N thanks for the answer.


What's the next question?

My name is Avinash.
Next question: -
There are many objects which have some color (e.g. red or some other) but when you crush it and make its powder, then it looks white. Why? I mean what does the color change?

As per my layman's knowledge, as an object is crushed into smaller particles, the particles reflect more light in all directions, n thus appear white, or near-white.