Define one watt hour.

Two bulbs $A$ and $B$ are rated as $90 \, W - 120 \, V$ and $60 \, W - 120 \, V$ respectively. They are connected in parallel across a $120 \, V$ source. Find the current in each bulb. Which bulb will consume more energy?

Two conductors,one having resistance $R$ and another $2R$ are connected in turn across a $dc$ source. If the rate of heat produced in the two conductors is $Q_{1}$ and $Q_{2}$ respectively,what is the value of $Q_{1} / Q_{2}$?

Name the commercial unit of electrical energy. Convert it into joule. What is the other name of the commercial unit?

In the following circuits (Figure),heat produced in the resistor or combination of resistors connected to a $12\, V$ battery will be

$(i)$ Name and state the law that gives the relationship between the current through a conductor and the potential difference across its two terminals. Also,express this law mathematically.
$(ii)$ Draw the $V-I$ graph for this law. Justify your answer.
$(iii)$ Write the name and use of the circuit components whose symbols are given below:
$(a)$ $A$ resistor with an arrow through it.
$(b)$ $A$ circle with a dot inside,connected to two lines.