Posted in: Physics | Date: 12th Jul'17
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To hear an echo, the sound wave has to reach an obstacle and then return back to you. Now let the distance between you and the obstacle be d. The that sound travels to let you hear echo is 2*d. Let the speed of sound be v and the time taken by sound to go to the obstacle and return back to you be t. Therefore we can write:
2*d = v*t
or, d=v*t/2
Now humans cannot hear two sounds distinctly unless there is a time gap of 0.1s b/w the two. Now putting t=.1, we get:
d=v*0.1/2
or, d= v*0.05
Now if we are trying to hear echo in air, then v is approximately 343m/s. So the minimum distance required to hear an echo in air is achieved by:
d=343*0.05
or, d=17.15
Therefore to hear echo in air at room temperature, the minimum distance is 17.15m.
This will vary if the media through which sound is travelling changes or if the temperature is changed or if any other living being is considered instead of humans hearing it. Posted in: Physics | Date: 12th Jul'17
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A low pass filter allows all signals with frequency lesser than a certain cut off frequency (a frequency to which the filter is tuned to) and attenuates the frequency greater than the cut off frequency to a such an extent that it seems to disappear.
High pass filter does just the opposite thing. Posted in: Physics | Date: 12th Jul'17
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Yes by 180degrees. Posted in: Physics | Date: 12th Jul'17
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The question would have been does light have information or not. Imagine a planet a million light years away from us. Only a small part of the light from our planet is reaching it now. If we could gather all the light rays via a very large convex lens and focus it on the far away planet what would they see? They would see dianosours roaming on the earth's surface. Thus light ray contain information and also it is a way or the only way of time travel. Posted in: Physics | Date: 12th Jul'17
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Instead of connecting the chords of the mic to a loudspeaker, connect it to the ports of a C.R.O. then you will get it.
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The answer is 1215.50. When the compound interest is calculated half yearly, the formula for amount is:
A=P*(1+r/200)^2*n
P-principal
r-rate of interest
n-time in years
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4. None of them. This is because it is the set having all the elements of set A and set B without repetition. Therefore the Cardinal no. of union set might or might not match with the sum of the Cardinal nos. if set A and set B.
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2. Set if all natural nos that add up to 0. This is because natural nos are greater than 0 so they can't add up to 0. 
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