1
JEE Main 2018 (Online) 15th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
JEE Main 2018 (Online) 15th April Morning Slot Physics - Current Electricity Question 255 English
In a meter bridge, as shown in the figure, it is given that resistance $$Y = 12.5\,\,\Omega $$ and that the balance is obtained at a distance $$39.5$$ $$cm$$ from end $$A$$ (by Jockey J). After interchanging the resistances $$X$$ and $$Y$$, a new balance point is found at a distance $${l_2}$$ from end $$A.$$ What are the value of $$X$$ and $${l_2}$$ ?
A
$$8.16\,\,\Omega $$ and $$60.5$$ $$cm$$
B
$$19.15\,\,\Omega $$ and $$39.5$$ $$cm$$
C
$$8.16\,\,\Omega $$ and $$39.5$$ $$cm$$
D
$$19.15\,\,\Omega $$ and $$60.5$$ $$cm$$
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 2018 (Online) 15th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The $$B$$-$$H$$ curve for a ferromagnet is shown in the figure. The ferromagnet is placed inside a long solended with $$1000$$ turns/cm. The current that should be passed in the solended to demagnetise the ferromagnet completely is :

JEE Main 2018 (Online) 15th April Morning Slot Physics - Magnetic Properties of Matter Question 48 English
A
$$1$$ $$mA$$
B
$$2$$ $$mA$$
C
$$20\,\mu A$$
D
$$40\,\mu A$$
4
JEE Main 2018 (Online) 15th April Morning Slot
MCQ (Single Correct Answer)
+4
-1
Change Language
The equivalent capacitance between $$A$$ and $$B$$ in the circuit given below, is :

JEE Main 2018 (Online) 15th April Morning Slot Physics - Capacitor Question 117 English
A
$$2.4\,\mu F$$
B
$$4.9\,\mu F$$
C
$$3.6\,\mu F$$
D
$$5.4\,\mu F$$
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