What are the factors on which the resistivity of a material depends?

Should the resistance of an ammeter be low or high? Give reason.

Two electric bulbs $A$ and $B$ are marked $220\, V, 60\, W$ and $220\, V, 100\, W$ respectively. Which one of the two has greater resistance?

$A$ current of $1 \ A$ flows in a series circuit containing an electric lamp and a conductor of $5 \ \Omega$ when connected to a $10 \ V$ battery. Calculate the resistance of the electric lamp. Now,if a resistance of $10 \ \Omega$ is connected in parallel with this series combination,what change (if any) in the current flowing through the $5 \ \Omega$ conductor and the potential difference across the lamp will take place? Give reason.

$1 \text{ kWh} = 3.6 \times 10^6 \text{ joules}$. Is this statement true or false?

Name a device that can be used to maintain a potential difference across a conductor. Also,draw its circuit symbol.