1
JEE Main 2021 (Online) 1st September Evening Shift
+4
-1
There are two infinitely long straight current carrying conductors and they are held at right angles to each other so that their common ends meet at the origin as shown in the figure given below. The ratio of current in both conductor is 1 : 1. The magnetic field at point P is ____________. A
$${{{\mu _0}I} \over {4\pi xy}}\left[ {\sqrt {{x^2} + {y^2}} + (x + y)} \right]$$
B
$${{{\mu _0}I} \over {4\pi xy}}\left[ {\sqrt {{x^2} + {y^2}} - (x + y)} \right]$$
C
$${{{\mu _0}Ixy} \over {4\pi }}\left[ {\sqrt {{x^2} + {y^2}} - (x + y)} \right]$$
D
$${{{\mu _0}Ixy} \over {4\pi }}\left[ {\sqrt {{x^2} + {y^2}} + (x + y)} \right]$$
2
JEE Main 2021 (Online) 31st August Evening Shift
+4
-1
A current of 1.5 A is flowing through a triangle, of side 9 cm each. The magnetic field at the centroid of the triangle is :

(Assume that the current is flowing in the clockwise direction.)
A
3 $$\times$$ 10$$-$$7 T, outside the plane of triangle
B
$$2\sqrt 3$$ $$\times$$ 10$$-$$7 T, outside the plane of triangle
C
$$2\sqrt 3$$ $$\times$$ 10$$-$$5 T, inside the plane of triangle
D
3 $$\times$$ 10$$-$$5 T, inside the plane of triangle
3
JEE Main 2021 (Online) 31st August Evening Shift
+4
-1
The magnetic field vector of an electromagnetic wave is given by $$B = {B_0}{{\widehat i + \widehat j} \over {\sqrt 2 }}\cos (kz - \omega t)$$; where $$\widehat i,\widehat j$$ represents unit vector along x and y-axis respectively. At t = 0s, two electric charges q1 of 4$$\pi$$ coulomb and q2 of 2$$\pi$$ coulomb located at $$\left( {0,0,{\pi \over k}} \right)$$ and $$\left( {0,0,{{3\pi } \over k}} \right)$$, respectively, have the same velocity of 0.5 c $$\widehat i$$, (where c is the velocity of light). The ratio of the force acting on charge q1 to q2 is :-
A
$$2\sqrt 2 :1$$
B
$$1:\sqrt 2$$
C
2 : 1
D
$$\sqrt 2 :1$$
4
JEE Main 2021 (Online) 31st August Evening Shift
+4
-1
A coil is placed in a magnetic field $$\overrightarrow B$$ as shown below : A current is induced in the coil because $$\overrightarrow B$$ is :
A
Outward and decreasing with time
B
Parallel to the plane of coil and decreasing with time
C
Outward and increasing with time
D
Parallel to the plane of coil and increasing with time
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