Question

what is tharmal expansion , derive an expression for the linear or longitudianal expression​

Answer 1

Answer:

In physics, thermal expansion is the likelihood of matter to change in volume in response to a change in temperature. When a substance is heated, its basic particles move around more quickly and by doing so generally maintain a greater average separation.

Magnification, in optics, the size of an image relative to the size of the object creating it.

Linear (sometimes called lateral or transverse) magnification refers to the ratio of image length to

object length measured in planes that are perpendicular to the optical axis.

 

Longitudinal magnification denotes the factor by which an image increases in size,

as measured along the optical axis.

 

Linear magnification m = I/O = -v/u  

 

where I and O are the size of image and object respectively.

 

v and u are mirror-to-image distance and mirror-to-object distance respectively

 

Longitudinal magnification ml = I/O = -(v2 - v1) / (u2 - u1)  

 

By using the mirror equation,  (1/v1 ) + (1/u1 ) = (1/v2 ) + (1/u2 ) = 1/f  ,

we get  , ml = -(v2 - v1) / (u2 - u1) = (v1v2)/(u1u2) = m2