Four bulbs $B_1, B_2, B_3$ and $B_4$ of $100\, W$ each are connected to a $220\, V$ main supply as shown in the figure. The reading in an ideal ammeter will be ............... $A$.

If the galvanometer reading is zero,then the resistance $X = \dots \Omega$.

Two electric bulbs with ratings $25\, W - 220\, V$ and $100\, W - 220\, V$ are connected in series to a $440\, V$ supply. Which bulb will fuse?

Find the current through the $2\,\Omega$ resistance in the given circuit. (in $A$)

When a cell is connected to a resistance of $2\,\Omega$,the current flowing is $0.5\,A$. When it is connected to a resistance of $5\,\Omega$,the current flowing is $0.25\,A$. What is the $emf$ of the cell in $volt$?

The resistance of an iron wire is $10\,\Omega$ and the temperature coefficient of resistivity is $5 \times 10^{-3}\,^{\circ}C^{-1}$. At $20\,^{\circ}C$,it carries $30\,mA$ of current. Keeping the potential difference between its ends constant,the temperature of the wire is raised to $120\,^{\circ}C$. The current in milliamperes that flows in the wire is: