The electric potential of a positively charged body is positive,and the electric potential of a negatively charged body is negative.

If the cross-sectional area of a conducting wire is doubled,what will be the effect on its resistance?

How does the resistance of a wire vary with its cross-sectional area?

When do we say that the resistors are connected in series?

If three resistors of $5 \Omega$,$10 \Omega$,and $15 \Omega$ are connected in series,the equivalent resistance $R$ is equal to ........ (in $Omega$)

In a household,$5$ tube lights of $40 \text{ W}$ each are used for $5 \text{ hours}$ and an electric press of $500 \text{ W}$ for $4 \text{ hours}$ everyday. Calculate the total energy consumed by the tube lights and press in a month of $30 \text{ days}$.