1
JEE Main 2023 (Online) 31st January Morning Shift
+4
-1 A rod with circular cross-section area $$2 \mathrm{~cm}^{2}$$ and length $$40 \mathrm{~cm}$$ is wound uniformly with 400 turns of an insulated wire. If a current of $$0.4 \mathrm{~A}$$ flows in the wire windings, the total magnetic flux produced inside windings is $$4 \pi \times 10^{-6} \mathrm{~Wb}$$. The relative permeability of the rod is

(Given : Permeability of vacuum $$\mu_{0}=4 \pi \times 10^{-7} \mathrm{NA}^{-2}$$)

A
$$\frac{5}{16}$$
B
125
C
$$\frac{32}{5}$$
D
12.5
2
JEE Main 2023 (Online) 30th January Evening Shift
+4
-1 As shown in the figure, a current of $2 \mathrm{~A}$ flowing in an equilateral triangle of side $4 \sqrt{3} \mathrm{~cm}$. The magnetic field at the centroid $\mathrm{O}$ of the triangle is (Neglect the effect of earth's magnetic field)

A
$4 \sqrt{3} \times 10^{-4} \mathrm{~T}$
B
$4 \sqrt{3} \times 10^{-5} \mathrm{~T}$
C
$3 \sqrt{3} \times 10^{-5} \mathrm{~T}$
D
$\sqrt{3} \times 10^{-4} \mathrm{~T}$
3
JEE Main 2023 (Online) 30th January Evening Shift
+4
-1 A current carrying rectangular loop PQRS is made of uniform wire. The length $P R=Q S=5 \mathrm{~cm}$ and $P Q=R S=100 \mathrm{~cm}$. If ammeter current reading changes from I to $2 I$, the ratio of magnetic forces per unit length on the wire $P Q$ due to wire $R S$ in the two cases respectively $\left(f_{P Q}^I: f_{P Q}^{2 t}\right)$ is: A
1 : 4
B
1 : 3
C
1 : 2
D
1 : 5
4
JEE Main 2023 (Online) 30th January Morning Shift
+4
-1 A massless square loop, of wire of resistance $$10 \Omega$$, supporting a mass of $$1 \mathrm{~g}$$, hangs vertically with one of its sides in a uniform magnetic field of $$10^{3} \mathrm{G}$$, directed outwards in the shaded region. A dc voltage $$\mathrm{V}$$ is applied to the loop. For what value of $$\mathrm{V}$$, the magnetic force will exactly balance the weight of the supporting mass of $$1 \mathrm{~g}$$ ?

(If sides of the loop $$=10 \mathrm{~cm}, \mathrm{~g}=10 \mathrm{~ms}^{-2}$$) A
1 V
B
$$\frac{1}{10}$$V
C
10 V
D
100 V
JEE Main Subjects
Physics
Mechanics
Electricity
Optics
Modern Physics
Chemistry
Physical Chemistry
Inorganic Chemistry
Organic Chemistry
Mathematics
Algebra
Trigonometry
Coordinate Geometry
Calculus
EXAM MAP
Joint Entrance Examination