If the resistance of a conductor is doubled,the current is halved.

$A$ bulb is rated at $5.0 \text{ V}, 100 \text{ mA}$. Calculate its
$(i)$ power and $(ii)$ resistance.

$(a)$ 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?

You are given three equal resistors. The number of resistances which can be obtained by joining them in series and in parallel grouping is

In the figure given below,$A, B$,and $C$ are three ammeters. The ammeter $B$ reads $0.5\, A$. (All the ammeters have negligible resistance.) Calculate:
$(i)$ the readings in the ammeters $A$ and $C$.
$(ii)$ the total resistance of the circuit.

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