A potentiometer has a uniform wire of length $$5 \mathrm{~m}$$. A battery of emf $$10 \mathrm{~V}$$ and negligible internal resistance is connected between its ends. A secondary cell connected to the circuit gives balancing length at $$200 \mathrm{~cm}$$. The emf of the secondary cell is

The colour code for a carbon resistor of resistance $$0.2 \mathrm{k} \Omega \pm 10 \%$$ is

Each resistance in the given cubical network has resistance of $$1 \Omega$$ and equivalent resistance between $$A$$ and $$B$$ is

$$I-V$$ characteristic of a copper wire of length $$L$$ and area of cross-section $$A$$ is shown in figure. The slope of the curve becomes