1
JEE Main 2018 (Online) 15th April Evening Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A current of 1 A is flowing on the sides of an equilateral triangle of side 4.5 $$ \times $$ 10-2 m. The magnetic field at the center of the triangle will be :
A
2 $$ \times $$ 10-5 Wb/m2
B
Zero
C
8 $$ \times $$ 10-5 Wb/m2
D
4 $$ \times $$ 10-5 Wb/m2
2
JEE Main 2018 (Online) 15th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A Helmholtz coil has a pair of loops, each with $$N$$ turns and radius $$R$$. They are placed coaxially at distance $$R$$ and the same current $${\rm I}$$ flows through the loops in the same direction. $$P,$$ midway between the centers $$A$$ and $$C$$, is given by [Refer to figure given below] :

JEE Main 2018 (Online) 15th April Morning Slot Physics - Magnetic Effect of Current Question 146 English
A
$${{8N{\mu _0}{\rm I}} \over {{5^{1/2}}R}}$$
B
$${{8N{\mu _0}{\rm I}} \over {{5^{3/2}}R}}$$
C
$${{4N{\mu _0}{\rm I}} \over {{5^{1/2}}R}}$$
D
$${{4N{\mu _0}{\rm I}} \over {{5^{3/2}}R}}$$
3
JEE Main 2017 (Online) 9th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A negative test charge is moving near a long straight wire carrying a current. The force acting on the test charge is parallel to the direction of the current. The motion of the charge is :
A
away from the wire
B
towards the wire
C
parallel to the wire along the current
D
parallel to the wire opposite to the current
4
JEE Main 2017 (Online) 8th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
A magnetic dipole in a constant magnetic field has :
A
maximum potential energy when the torque is maximum.
B
zero potential energy when the torque is minimum.
C
zero potential energy when the torque is maximum.
D
minimum potential energy when the torque is maximum.
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