Draw a labelled circuit diagram showing three resistors $R_{1}, R_{2}$ and $R_{3}$ connected in series with $a$ battery $(E),$ a rheostat $(R h),$ $a$ plug key $(K)$ and an ammeter $(A)$ using standard circuit symbols. Use this circuit to show that the same current flows through every part of the circuit. List two precautions you would observe while performing the experiment.
The circuit diagram is as shown.
Join three resistors of different values in series. Connect them with a battery, an ammeter, a rheostat and a plug key, as shown in figure. Plug the key. Note the ammeter reading. Change the position of ammeter to anywhere in between the resistors. Note the ammeter reading each time. We observe that the value of the current in the ammeter is the same, independent of its position in the electric circuit. It means that in a series combination of resistors the current is the same in every part of the circuit or the same current through each resistor.
Precautions : $(i)$ The current should not be passed for a long time.
$(ii)$ All the connections should be tight.
The formula for an electric current is $.....$
$100 \,J$ of heat is produced each second in a $4\, \Omega$ resistance. Find the potential difference across the resistor.
Elements of electric toasters and electric iron are made of an alloy rather than a pure metal. Give two reasons to justify the statement.
Explain how do we classify materials as conductor and insulators on the basis of their resistance.
Find the number of electrons transferred between two points kept at a potential difference of $20\, V$ if $40\, J$ of work is done.