A rigid circular loop of radius r & mass m lies in the xy plane on a flat table and has a current I flowing in it At this particular place the earth's magnetic filed is `B =B_(x) hati +B_(y) hatj` How large must I be before one edge of the loop will lift from table
Repeat if ,`oversetrarr(B) = oversetrarr(B_(x)) hati + oversetrarr(B_(z)) hatk` .

Options

A. `(mg)/(pirsqrt(B_(x)^(2)+B_(z)^(2)))`
B. `(mg)/(pirB_(x))`
C. `(mg)/(pirB_(z))`
D. `(mg)/(pirsqrt(B_(x)B_(z)))`

Answer

2

Explanation

For the point `O B_(1)=((mu_(0)I_(c))/(2R))_(o.)`
`(` due to circular loop `)`
`B_(2)=((mu_(0)I_(c))/(2piH))_(o.)(` due to long straight wire `)`
Since `vec(B)_(1)` and `vec(B)_(2)` act in opposite direction for resultant magnetic field to be zero `B_(1)=B_(2)`
Hence, `H=(I_(1)R)/(I_(c)pi)`