Category: engineering

Oh my god laws of physics, this is literally m…

Oh my god laws of physics, this is literally my favorite meme of all times!

Regular

Regular

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The only way to finish college

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Pantograph and TrainsPantograph is a very interesting device…

Pantograph and Trains

Pantograph is a very interesting device that you may find on the roof of electric trains, trams or electric buses.

And the primary purpose that it serves is to collect power from the overhead power line to run the motors of the train without losing contact at higher speeds.

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The train takes the current
from the over head line and the current flows to the tracks
which are earthed at regular intervals via the axle brush on the train.

This completes the circuit.

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The overhead lines are kept in tension and dropper wires are placed at multiple locations to ensure that the contact wire does not bend under its own weight.

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And since any two objects that rub against each other, constant frictional contact would wear them out, the Pantograph and the contact wires have a sliding contact.

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This results in less wear for both the Pantograph and the contact wires resulting in lesser maintenance.

Graphite conducts electricity extremely well while also working great as a lubricant due to it’s self-lubricating properties and therefore most contact strips on the Pantographs are made up of Graphite.

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It’s a very simple apparatus with an extremely pivotal role and that’s what makes  the Pantograph special. Have a great day!

* Trolley pole

** Third Rail

*** Arcing is a serious problem when we are dealing with any high voltage lines. in bullet trains which operate under higher voltages, the Pantographs are always forced to be in contact with the contact wires through a dynamic lever-spring mechanism. (Source)

fuckyeahphysica: The Touch Screen One cozy evening, I gazed a…

fuckyeahphysica:

The Touch Screen

One cozy evening, I gazed a lazy look to the surrounding. From the looking glass of a Lazy individual everything looks dull.

But once my vision tuned in on the Smart Phone, it struck me that I had no idea how this thing works but yet have been using it constantly for years. Time to disparage the boredom !

This is an account of the bewitching touch screen world. All Aboard!

The Resistive Touch Screen

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If you have used a mobile phone in the distant past that involves you pressing down hard on the screen, then there is a great possibility you have used a Resistive touch screen.

Some examples are the Nokia N800, Nokia N97, HTC Tattoo, Samsung Jet or the Nintendo DS.

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How does it work?

This is the traditional form of a touch screen and its working is rather blunt. There are two conductive sheets present that are separated by spacers.

When you press your hand against the screen , the top layer gets pressed and
makes contact with the bottom layer. This completes an electrical
circuit.

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The act of pressing reduces the resistance between the two conductive plates. (because you are reducing the distance between these two conductive plates and resistance is dependent on the length of the medium)

The voltage established as a result of this change in resistance is measured and the coordinates of the point of contact are determined.

The harder you press, the more the change in resistance.

This is one of the frustrating things about this type of touch screen.

Resistive touchscreen require slight pressure
in order to register the touch, and are not always as quick to respond.

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But they are used in many low-budget mobile phones like the Freedom 251, which is a touch screen phone for $3.75.

The Capacitive Touch Screen

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Now over to the touch screen that we are most accustomed with: the capacitive type.

Capacitive touch screens are constructed from materials like copper or indium tin oxide that store electrical charges in an electrostatic grid of tiny wires, each smaller than a human hair

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When a finger hits the screen a tiny electrical charge is transferred to
the finger to complete the circuit, creating a voltage drop on that
point of the screen.

Due to the transfer of some amount of charge from the screen to your
body. this change will be noted by the monitor placed below the screen
and the exact location of your touch is noted.

Note:

Plastic does not allow charges to flow through. Ergo, if you try to use it whilst wearing gloves or anything plastic / non-conductive materials, the screen will not respond to your touch!

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But leather or other conductive materials on the other hand will allow charges to pass through, which is why they work well with any smart phone.

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Hope you guys enjoyed this post . Have a good day!

* Some of these facts may not apply to Rugged phones like the CAT S61 or its variants.

The exotic moves of the human eyeIt is always a humbling…

The exotic moves of the human eye

It is always a humbling experience to compare our progress in technology with what nature has been doing for decades on end.

1-2 –> Iris in camera vs human eye

3-4 –> Iris mechanism in camera vs human eye

5-6 –> Accommodation of the eye

Have a good one!

* Pupil dilation video

* Eye contraction video

* Understanding the functioning of the Eye

* Bio-mimicry and eyes

Aircraft operations in Infrared

Taxing

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Take-off

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Landing

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Reverse Thrust

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Deicing

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For more interesting aircraft action in IR check out these videos:

* Aircraft inspections in Infrared

** Takeoff, landing and more – as seen from cockpit using IR camera

*** Landing with and without FLIR (Forward Looking Infrared Radar) 

If unit vectors always scared you for some reason, this neat…

If unit vectors always scared you for some reason, this neat little trick  from The story of i by Paul Nahin involving complex numbers is bound to be a solace.

It allows you find the tangential and radial components of acceleration through simple differentiation. How about that! 

Have a good one!

** r = r(t),  θ =  θ(t)