00:00Numerical number 7 of unit 18 magnetic fields is find the current in a long straight wire
00:18that would produce a magnetic field twice the strength of the earth at a distance of
00:275.0 centimeter from the wire is magnetic field of earth is given which is 5.0 into 10 raised
00:38power minus 5 tesla is question my care i a k am a current calculate karna hai long straight
00:47wire ka jo magnetic field produce karai hai twice of the earth's magnetic field or
00:57distance bhi hume obtained hai which is 5.0 centimeter from the wire or earth ki magnetic field bhi hume
01:07obtained hai which is 5.0 into 10 raised power minus 5 tesla so sab se phele hai hum data
01:14as we have to calculate current i and the magnetic field which is produced is twice the magnetic field
01:35of earth means b is equal to the twice of the magnetic field of earth so magnetic field of earth is given
01:46which is 2 into 5.0 into 10 raised power minus 5 tesla
02:04so magnetic field will be equal to
02:062 into 2 into 5 means 10 into 10 raised power minus 5 tesla we can also write this as
02:171 into 10 raised power minus 4 tesla
02:24so magnetic field of earth power minus 5 tesla minus 5 tesla minus 5 tesla minus 4
02:43which is five centimeters so this will be 4 into 10 meters
02:47So, we will convert this meter to convert this meter, we will divide 100 because 1 centimeter is equal to 1 upon 100 meter, so it will be 0.05 meter, so for solution or calculation,
03:07we will use the formula is, d is equal to mu 0 i upon 2 pi r,
03:25so by rearranging this equation, i will be equal to b into 2 pi r divided by mu 0 means permeability of free space,
03:49because here we divide 2 pi r, so we will multiply this side, so it will be b into 2 pi r and mu 0 i with multiply it,
04:01so here we will divide it, so the final form of this equation will be is, mu 0 value constant is,
04:12means permeability of free space ka value constant is, the value of mu 0 is constant which is 4 pi into 10 is power minus 7 tesla into meter per ampere,
04:30now by putting the values, the value of b is, 1 into 10 is power minus 4 tesla multiplied with 2 pi r,
04:47the value of r is, the value of r is, the value of r is, 0.05 meter divided by,
04:52divided by,
04:54and mu 0 ka value value 4 pi into 10 is power minus 7,
05:04pi pi ke saath cancel hojaegi,
05:06and 2 ka table 2 per 1 time,
05:09and 4 per 2 times hooga,
05:11is, i will be equal to, 1 into 10 is power minus 4, multiplied with 0.05, divided by,
05:232 into 10 is power minus 7,
05:26so, jab am in ko simplify kareenge,
05:30so then, we will get final answer is, 25 years,
05:3528 years,
05:3622 years,
05:37so, this is our final answer.
05:41j
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