Question

A cell of emf E and intemal resistance r is connected across a variable resistor R. Plot a graph showing the
variation of terminal potential V with resistance R. Predict from the graph, the condition under which V
becomes equal to E.​

Answer 1

repeated exposure to heat and copious amounts of rainfall. A haboob -- a violent desert dust storm -- sandblasts rocks into fine particles of sand, but not as fast as the rate of weathering that occurs in tropical climates.

Chemical, Physical and Biological Weathering

Weathering occurs one of three ways: through physical processes such as freezing and thawing, because of live organisms whose roots break rocks or through chemical processes that occur when carbon dioxide in the soil and air and mixes with water and specific minerals in rocks to form a weak acid that reduces rocks into silt, soil and sediment.

Chemical weathering typically increases as temperatures rise and rain falls, which means rocks in hot and wet climates experience faster rates of chemical weathering than do rocks in cold, dry climates.

Physical weathering occurs more often in cold climates, because the different minerals within rocks expand and contract at different rates when they are heated and cooled. Repeated heating and cooling cycles eventually cause rocks to fracture. Desert and mountain climates experience a wide range of temperatures from low to high during a day and night, which accounts for the breakdown of rocks known as physical weathering.

Biological weathering occurs when living organisms break up rocks. Tree roots, for example, can fracture rocks in the same way they buckle pavement. Warm, humid climates are most favorable to life. Contrast the rich diversity of life in a rainforest, for example, with the scarcity of life in the dry Sahara or the frigid Antarctic. Consequently, rates of biological weathering are most rapid in warm humid climates like those in tropical regions.