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

Derive an expression for equivalent resistance when three resistors of resistance $R_{1}, R_{2}$ and $R_{3}$ are connected in parallel.

Insulators like wood and rubber have a very low electrical resistance.

If $10$ bulbs of $100 \ W$ each are kept on for $1 \ \text{hour}$, how much electrical energy is consumed?

Resistance of a metal wire of length $1\, m$ is $26\, \Omega$ at $20^{\circ} C$. If the diameter of the wire is $0.3\, mm$,what will be the resistivity of the metal at that temperature?

Draw a schematic diagram of an electric circuit (in the "on" position) consisting of a battery of five cells of $2\, V$ each, a $5\, \Omega$ resistor, a $8\, \Omega$ resistor, a $12\, \Omega$ resistor and a plug key, all connected in series. An ammeter is put in the circuit to measure the electric current through the resistors and a voltmeter is connected so as to measure the potential difference across the $12\, \Omega$ resistor.
Calculate the reading shown by the
$(a)$ ammeter
$(b)$ voltmeter in the given electric circuit.