What is the symbol used to denote the unit of resistance,ohm?

The resistivity of semiconductor materials is $..........$.

Why should the melting point of a fuse wire be low?

In a Voltaic cell,what is the positive electrode (cathode) made of?

You are given three resistors of $10\, \Omega, 10\, \Omega, 20\, \Omega$,a battery of emf $2.5\, V$,a key,an ammeter,and a voltmeter. Draw a circuit diagram showing the correct connections of the given components such that the voltmeter gives a reading of $2.0\, V$.

Electric current flows through three lamps when arranged in $(a)$ a series and $(b)$ a parallel circuit. If the filament of one lamp breaks,explain what happens to the other two lamps in both cases.