## BOARD QUESTIONS FROM WAVE OPTICS (CBSE/AISSCE)

Practising the previously asked questions is a good idea to prepare for the exams.

## Car in a negative super elevation roundabout

“Can some one draw the free body diagram for a car travelling in a negative superelevation roundabout with friction considered? ?  What is the max and min speed for not skidding??”

## space flight propulsion

I understand that space in a vacuum, and is extremely cold. I understand that to push something trough space such as a rocket you need to create a force. Now I’ve researched many new technologies such as ion propulsion, nuclear antimatter reactors, etc. But they all still require a fuel. I want to know if it is possible to make two magnetic fields oppose each other in a chamber then harness the heat and use that a a propulsion. Also another though is can solar rays be harnessed and produce gamma radiation and use that as a force?

Posted Ethan Appleton

## calculating number of turns

How to determine the number of turns needed to generate specific magnetic field?
my condition is that the area of the magnet field strength must be able to sense a magnet material which is placed 4meters away from it. And voltage applied is 2.6v. Is there any formula?

The question is not very clear. Is it a single loop whose area is to be determined or whether the area is given and no. of turns to be calculated?

Anyway, I am giving here the formulae.

If, V is given, then current can be calculated if R is given.

Use this online calculator to solve your question, if you have necessary data.

http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/curloo.html

If any clarifications required please post as comment to this post.

## incorporation of thermodynamics in einsteins equation

Can we incorporate thermodynamic concepts of enthalpy (and entropy)in Einsteins equation “E=mC2?

it will become something like:
dE/dt=C²/h (dU/dt+dW/dt)

Where ,
h= enthalpy of the system
U= total internal energy
W=total work done

is is possible?

## circular motion

Is a body moving with constant angular velocity in circular path is example of accelerated motion?

Yes. Because acceleration is defined as the rate of change of velocity. Though the speed of a body in uniform circular motion is constant, the velocity goes on changing due to the continuous change in direction.

## ultrasound and mobile communication

sir, Animals like bat and dolphins use ultrasonic sound waves to know what all are in there way , we humans also use ultrasonic sound eg- radio , mobile network etc ..

my question is that did bats like animals can here what all we talk in your mobile ?

pls avoid if it is a stupid question

Posted Sheen

We are using Microwaves/ radio waves with the audiowaves superimposed on them to communicate. (Modulation) The voice signals are modulated with MW/Radio waves and transmitted. The modulated signals are received by the antenna at receiving end and demodulated (the radio waves are removed and audio signals extracted) and the voice signals are regenerated. But in the case of bats, they are producing and hearing (or say sensing) the ultrasound just like a radar to navigate and find the prey

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