Physics Questions

Magma is injected into surrounding rock forming an igneous intrusive.

Actually it is a plutonic formation in which magma present beneath Earth surface deforms the shape of rocks present above it
 

All automobiles uses satellite communication channel for their GPS devices.

Black  surfaces are good emitters of heat ( They are also good absorbers of heat). If the black surface is rough too, the emitting will be better. So (b) is the correct answer. Shining surfaces reflect back radiation. So if the black surface is also shining the effectiveness of emitting heat is lessened.

The size of gear is usually specified by pitch circle diameter.

p type of semiconductor is obtained when Silicon is doped with a trivalent impurity like Aluminium. Aluminium is a p-type dopant, which means that when a semiconductor i.e. silicon is doped with aluminium, it creates a hole (positively charged carrier) by accepting an electron from the silicon atom. Electrical conductivity of semiconductors increasesand resistivity remains the same

Echolocation is an adaptation bats use to hunt insects in flight, locate flowering plants and find warm places for hibernation.