1
JEE Main 2018 (Online) 15th April Morning Slot
+4
-1

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
+4
-1
In the given circuit all resistances are of value $$R$$ $$ohm$$ each. The equivalent resistance between $$A$$ and $$B$$ is :

A
$$2R$$
B
$$3R$$
C
$${{5R} \over 3}$$
D
$${{5R} \over 2}$$
3
JEE Main 2017 (Online) 9th April Morning Slot
+4
-1
A uniform wire of length 1 and radius r has a resistance of 100 $$\Omega$$. It is recast into a wire of radius $${r \over 2}.$$ The resistance of new wire will be :
A
1600 $$\Omega$$
B
400 $$\Omega$$
C
200 $$\Omega$$
D
100 $$\Omega$$
4
JEE Main 2017 (Online) 9th April Morning Slot
+4
-1
In a meter bridge experiment resistances are connected as shown in the figure. Initially resistance P = 4 $$\Omega$$ and the neutral point N is at 60 cm from A. Now an unknown resistance R is connected in series to P and the new position of the neutral point is at 80 cm from A. The value of unknown resistance R is :

A
$${{33} \over 5}\,\Omega$$
B
6 $$\,\Omega$$
C
7 $$\,\Omega$$
D
$${{20} \over 3}\,\Omega$$
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