Out of the two,a toaster of $1\, kW$ and an electric heater of $2\, kW$,which has a greater resistance?

Calculate the number of electrons constituting one coulomb of charge. (Charge on one electron $= 1.6 \times 10^{-19} \text{ C}$)

$A$ torch bulb is rated $5\,V$ and $500\,mA$. Calculate its $(i)$ power,$(ii)$ resistance,and $(iii)$ energy consumed when it is lighted for $4$ hours.

$(a)$ 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?

If the charge on an electron is $1.6 \times 10^{-19} \text{ C}$,find the approximate number of electrons in $1 \text{ C}$.

The resistivity of all pure metals increases with an increase in temperature.