Explain in brief about seismograph. Also, draw a labelled diagram of a seismograph.

A glass rod is rubbed with a silk cloth and an inflated rubber balloon is rubbed with a woolen cloth. Out of glass rod, inflated rubber, silk cloth and woolen cloth:

Mention the name of two objects acquires a negative charge. Why?

A glass rod is rubbed with a silk cloth and an inflated rubber balloon is rubbed with a woolen cloth. Out of glass rod, inflated rubber, silk cloth and woolen cloth:

Mention the name of two objects acquires a positive charge. Why?

We should use mobile phones rather than landline phones during a thunderstorm. Give reasons.