In the ionsphere , electrons execute 1.4×10^6 revolution in a second. Find the strength of the magnetic flux density B in this region ​

Could someone . i have tried to solve myself but my calculation is off

In the first law of thermodynamics, triangle e=q-w, what does q stand for

Two rigid transformations are used to map δhjk to δlmn. the first is a translation of vertex h to vertex l. what is the second transformation? a reflection across the line containing hk a rotation about point h a reflection across the line containing hj a rotation about point k