What is an electric fuse? How does it protects devices and appliances from damage?

What is valency? How does it vary along the period?

What does an electric circuit mean?

How does protophloem differ from metaphloem?

What is hearing aid? How does hearing aid work?

What are depressants? How does NaCN act as depressant in preventing ZnS from forming froth?

What is the conventional direction of current? How does it differ from the actual motion of charge carrier inside a current-carrying conductor?

What is periderm? How does periderm formation take place in dicot stem?

What is electronegativity of an element? How does electromegativity vary in a period and in a group in the periodic table?