How does an electric current flow in a closed circuit? Explain.

An electric oven of $3 \mathrm{kW}$ is connected to the mains of $220 \mathrm{V}$. Calculate:

The amount of energy consumed if the oven is switched on for an hour.

An electric oven of $3 \mathrm{kW}$ is connected to the mains of $220 \mathrm{V}$. Calculate:

The cost of electrical energy consumed if the cost per unit is $\mathrm{Rs}. 6.50$ and if the oven is switched on for an hour.

When four identical electric bulbs are connected as shown in figure A, they glow with normal brightness. Which of the following statements is correct when these bulbs are connected as shown in figure B?

Give reasons for the following.

Birds do not get electrocuted when they perch on power lines.

Give reasons for the  following:

Nichrome wire is used as a heating element instead of copper wire.