Two electric lamps of $100\, W$ and $25\, W$ respectively are joined in parallel to a supply of $200\, V$. Calculate the total current flowing through the circuit. (in $, A$)

How is alternating current $(AC)$ different from direct current $(DC)$?

$(a)$ Name an instrument that measures electric current in a circuit. Define the unit of electric current.
$(b)$ What do the following symbols mean in an electric circuit?
$(c)$ Draw a closed circuit diagram consisting of a $0.5\, m$ long nichrome wire $XY$,an ammeter,a voltmeter,four cells of $1.5\, V$ each,and a plug key.

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 the $4\,\Omega$ resistor.
$(c)$ Potential difference across the $4\,\Omega$ resistor.
$(d)$ Power dissipated in the $4\,\Omega$ resistor.
$(e)$ Difference in ammeter readings,if any.

$(a)$ Derive an expression to find the equivalent resistance of three resistors connected in series. Also,draw the schematic diagram of the circuit.
$(b)$ Find the equivalent resistance of the following circuit.

$A$ hot plate of an electric oven connected to a $220\, V$ line has two resistance coils $A$ and $B$,each of $24\,\Omega$ resistance,which may be used separately,in series,or in parallel. What are the currents in the three cases?