Two conducting wires of the same material and of equal lengths and equal diameters are first connected in series and then parallel in a circuit across the same potential difference. The ratio of heat produced in series and parallel combinations would be -

An electric iron of resistance $20\, \Omega$ takes a current of $5\, A$. Calculate the heat developed in $30\, s$.

What is meant by saying that the potential difference between two points is $1$ $V$?

Compute the heat generated while transferring $96000$ coulomb of charge in one hour through a potential difference of $50\, V$.

Draw a schematic diagram of a circuit consisting of a battery of three cells of $2\, V$ each,a $5 \,\Omega $ resistor,an $8\,\Omega $ resistor,and a $12\,\Omega $ resistor,and a plug key,all connected in series.

An electric lamp of $100 \,\Omega$,a toaster of resistance $50 \,\Omega$,and a water filter of resistance $500 \,\Omega$ are connected in parallel to a $220 \,V$ source. What is the resistance of an electric iron connected to the same source that takes as much current as all three appliances,and what is the current through it?