What is the resistance of an ideal ammeter?

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

What is the main principle involved in a Voltaic cell?

Calculate the resistance of an electric bulb which allows a $10 \ A$ current when connected to a $220 \ V$ power source. (in $Omega$)

An electric oven hot plate is connected to a $200 \, V$ line. It has two resistance coils $A$ and $B$,each of $30 \, \Omega$,which may be used separately,in series,or in parallel. Find the value of the current required in each of the three cases.

An electric heater rated $1200 \ W$ operates $2 \ h$ per day. Find the cost of the energy required to operate it for $30$ days at ₹ $5.00$ per unit.