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 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)

The value of current in the 6 $$\Omega$$ resistance is :

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 :