Why is tungsten metal selected for making filaments of incandescent lamps?

Draw a labelled circuit diagram showing three resistors $R_{1}, R_{2}$ and $R_{3}$ connected in series with a battery $(E)$,a rheostat $(Rh)$,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.

Study the $V - I$ graph for a resistor as shown in the figure and prepare a table showing the values of $I$ (in amperes) corresponding to four different values of $V$ (in volts). Find the value of current $I$ (amperes) for $V=10$ volts. How can we determine the resistance of the resistor from this graph?

$(a)$ Explain why a conductor offers resistance to the flow of current.
$(b)$ Differentiate between conductor,resistor,and resistance.

$A$ bulb gets dimmer for a moment when a geyser,connected across the same source,is switched on. Why?

$(a)$ Derive the formula for the calculation of work done when current flows through a resistor.
$(b)$ One electric bulb is rated $40 \ W$ and $240 \ V$ and another is $25 \ W$ and $240 \ V$. Which bulb has higher resistance and how many times?