Why does resistance of conductor increases with increase in length of conductor area of cross section remaining same?

In the figure shown, what is the current (in ampere) drawn from the battery? You are given:
$R_1=15 \mathrm{\Omega }\mathrm{ }, R_2=10 \mathrm{\Omega }\mathrm{ }, R_3=20 \mathrm{\Omega }\mathrm{ }, R_4=5 \mathrm{\Omega },\mathrm{ }{R}_5=25 \mathrm{\Omega },\mathrm{ }{R}_6=30 \mathrm{\Omega },\mathrm{ }E=15 \mathrm{V}$

In the circuit shown below, a student performing Ohm's law experiment accidentally puts the voltmeter and the ammeter as shown in the circuit below; the reading in the voltmeter will be close to

In a conductor, if the number of conduction electrons per unit volume is $8.5\times {10}^{28}{\mathrm{m}}^{-3}$ and mean free time is $25f\mathrm{s}$ (femtosecond), its approximate resistivity is: $\left({\mathrm{m}}_{\mathrm{e}}=9.1\times {10}^{-31}\mathrm{k}\mathrm{g}\right)$