What is the resistance of an electric arc lamp,if the lamp uses $20\, A$ when connected to a $220\, V$ line?

The equivalent resistance in series combination is

An electric appliance draws a current of $0.4\, A$ when the voltage is $200\, V$. Calculate the amount of charge flowing through it in one hour.

What is the formula to find electric power $P$?

$(a)$ 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?

Three bulbs of $40\, W$,$60\, W$,and $100\, W$ are connected in series across the mains. Across which bulb is the potential difference highest? Across which is it lowest?