Explain secondary cells with the help of an example.

Write in brief the basic principle of hydroelectric power generation.

What type of energy is transformed to electrical energy in a dynamo?

Write the conventional symbol of the following component used in electric circuit diagram-

An electric cell

Answer the following:

What is the frequency of household alternating current $\left(\mathrm{AC}\right)$ in India?

Explain the working of Daniel cell with a neat diagram.

Consider an electrical conductor connected across a potential difference $V.$ Let $\Delta q$ be a small charge moving through it in time $\Delta t$. If $I$ is the electric current through it,
(i) the kinetic energy of the charge increases by $IV\Delta t$
(ii) the electric potential energy of the charge decreases by $IV\Delta \mathrm{t}$.
(iii) the thermal energy of the conductor increases by $IV\Delta \mathrm{t}$.

Then the correct statements is/are