What is the resistance of insulating materials?

What is a voltmeter? How is it connected in a circuit?

State $Ohm's$ law. Calculate the resistance of a conductor,if the current flowing through it is $0.2 \, A$ when the applied potential difference is $0.8 \, V$.

$V-I$ graphs for two wires $A$ and $B$ are shown in the figure. If both the wires are made of the same material and are of equal thickness,which of the two is of more length? Give justification for your answer.

$A$ current of $1 \ A$ flows in a series circuit containing an electric lamp and a conductor of $5 \ \Omega$ when connected to a $10 \ V$ battery. Calculate the resistance of the electric lamp. Now,if a resistance of $10 \ \Omega$ is connected in parallel with this series combination,what change (if any) in the current flowing through the $5 \ \Omega$ conductor and the potential difference across the lamp will take place? Give reason.

Find out the following in the electric circuit given in the figure:
$(a)$ Effective resistance of two $8\, \Omega$ resistors in the combination.
$(b)$ Current flowing through $4\, \Omega$ resistor.
$(c)$ Potential difference across $4\, \Omega$ resistor.
$(d)$ Power dissipated in $4\, \Omega$ resistor.
$(e)$ Difference in ammeter readings,if any.