Understand Brownian Motion. Click on the link to Watch the VIDEO explanation: Watch Video
The first evidence that matter consists of tiny particles in motion was given by English Botanist Robert Brown. When he was studying the pollen grains suspended in a liquid using a microscope, he discovered that pollen grains went dancing to and fro in a random manner. Similar haphazard motion can also be observed when small colloidal particles suspended in a liquid are seen under a powerful microscope. This zigzag motion is due to the unequal bombardment between suspended particles and molecules of surrounding medium. This irregular motion of suspended particles is referred to as Brownian Motion. We shall now study movements of large and small particles suspended in liquids. Let us look at a large particle A suspended in a solution. A no. of molecules hit A from all side. On an average the impact mutually cancelled out. So the resultant force on particle is zero. Now look at particle B which is very small. It is hit by less no. of molecules. Also it is not hit equally by all sides. So there is a resultant force which alters the direction of particle B. When it moves the direction of resultant force also changes resulting in a zigzag motion. Let us look at an experiment. Fill a hollow glass cube with small particles. Placed it under a low power microscope. Simultaneously illuminate the cube with a light source. We observe smoke particles appears as bright particles moving in all directions in black background. This is an experiment of Brownian Motion.
The first evidence that matter consists of tiny particles in motion was given by English Botanist Robert Brown. When he was studying the pollen grains suspended in a liquid using a microscope, he discovered that pollen grains went dancing to and fro in a random manner. Similar haphazard motion can also be observed when small colloidal particles suspended in a liquid are seen under a powerful microscope. This zigzag motion is due to the unequal bombardment between suspended particles and molecules of surrounding medium. This irregular motion of suspended particles is referred to as Brownian Motion. We shall now study movements of large and small particles suspended in liquids. Let us look at a large particle A suspended in a solution. A no. of molecules hit A from all side. On an average the impact mutually cancelled out. So the resultant force on particle is zero. Now look at particle B which is very small. It is hit by less no. of molecules. Also it is not hit equally by all sides. So there is a resultant force which alters the direction of particle B. When it moves the direction of resultant force also changes resulting in a zigzag motion. Let us look at an experiment. Fill a hollow glass cube with small particles. Placed it under a low power microscope. Simultaneously illuminate the cube with a light source. We observe smoke particles appears as bright particles moving in all directions in black background. This is an experiment of Brownian Motion.
No comments:
Post a Comment