An electric heater rated $1200 \ W$ operates $2 \ h$ per day. Find the cost of the energy required to operate it for $30$ days at ₹ $5.00$ per unit.

The formula for an electric current is $.....$

$(a)$ Name an instrument that measures electric current in a circuit. Define the unit of electric current.
$(b)$ What do the following symbols mean in circuit diagrams?
$(c)$ An electric circuit consisting of a $0.5 \ m$ long nichrome wire $XY$,an ammeter,a voltmeter,four cells of $1.5 \ V$ each and a plug key was set up.
$(i)$ Draw a diagram of this electric circuit to study the relation between the potential difference maintained between the points $X$ and $Y$ and the electric current flowing through $XY$.
$(ii)$ The following graph was plotted between $V$ and $I$ values. What would be the values of $V/I$ ratios when the potential difference is $0.8 \ V$,$1.2 \ V$ and $1.6 \ V$ respectively? What conclusion do you draw from these values?

Which symbol is used for the resistivity of a conductor?

What are the units of resistance?

$(i)$ Draw a circuit diagram to show how two resistors are connected in series.
$(ii)$ In a circuit,if two resistors of $5 \ \Omega$ and $10 \ \Omega$ are connected in series,how does the current passing through the two resistors compare?