1
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$$\Omega$$
2
JEE Main 2021 (Online) 20th July Morning Shift
+4
-1

The value of current in the 6 $$\Omega$$ resistance is :
A
4A
B
8A
C
10A
D
6A
3
JEE Main 2021 (Online) 18th March Morning Shift
+4
-1
In the experiment of Ohm's law, a potential difference of 5.0 V is applied across the end of a conductor of length 10.0 cm and diameter of 5.00 mm. The measured current in the conductor is 2.00 A. The maximum permissible percentage error in the resistivity of the conductor is :
A
3.9
B
8.4
C
7.5
D
3.0
4
JEE Main 2021 (Online) 17th March Evening Shift
+4
-1
Two cells of emf 2E and E with internal resistance r1 and r2 respectively are connected in series to an external resistor R (see figure). The value of R, at which the potential difference across the terminals of the first cell becomes zero is

A
r1 $$-$$ r2
B
$${{{r_1}} \over 2} - {r_2}$$
C
$${{{r_1}} \over 2} + {r_2}$$
D
r1 + r2
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