1
JEE Main 2021 (Online) 25th July Evening Shift
+4
-1
Out of Syllabus
The given potentiometer has its wire of resistance 10$$\Omega$$. When the sliding contact is in the middle of the potentiometer wire, the potential drop across 2$$\Omega$$ resistor is :

A
10 V
B
5 V
C
$${{40} \over 9}$$ V
D
$${{40} \over 11}$$ V
2
JEE Main 2021 (Online) 25th July Morning Shift
+4
-1
Out of Syllabus
In the given figure, there is a circuit of potentiometer of length AB = 10 m. The resistance per unit length is 0.1 $$\Omega$$ per cm. Across AB, a battery of emf E and internal resistance 'r' is connected. The maximum value of emf measured by this potentiometer is :

A
5 V
B
2.25 V
C
6 V
D
2.75 V
3
JEE Main 2021 (Online) 22th July Evening Shift
+4
-1
A Copper (Cu) rod of length 25 cm and cross-sectional area 3 mm2 is joined with a similar Aluminium (Al) rod as shown in figure. Find the resistance of the combination between the ends A and B.

(Take Resistivity of Copper = 1.7 $$\times$$ 10$$-$$8 $$\Omega$$m and Resistivity of Aluminium = 2.6 $$\times$$ 10$$-$$8 $$\Omega$$m)

A
0.0858 m$$\Omega$$
B
1.420 m$$\Omega$$
C
0.858 m$$\Omega$$
D
2.170 m$$\Omega$$
4
JEE Main 2021 (Online) 20th July Morning Shift
+4
-1
A current of 5 A is passing through a non-linear magnesium wire of cross-section 0.04 m2. At every point the direction of current density is at an angle of 60$$^\circ$$ with the unit vector of area of cross-section. The magnitude of electric field at every point of the conductor is :

(Resistivity of magnesium $$\rho$$ = 44 $$\times$$ 10$$-$$8 $$\Omega$$m)
A
11 $$\times$$ 10$$-$$5 V/m
B
11 $$\times$$ 10$$-$$3 V/m
C
11 $$\times$$ 10$$-$$7 V/m
D
11 $$\times$$ 10$$-$$2 V/m
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