An infinitely long circular rod of radius r contains a uniform charge density \rho . use guass's law to find the electric field for r> r and r< r .

this is an electrodynamics exercise, i hope you can give as much detail as possible

Sublimation- which change of state is shown in model

Ohm's law tells you that i = v/r where v is equivalent voltage and r is equivalent resistance of the circuit
since all circuits have the same voltage, your question is really asking which circuit has the lowest total resistance, since the lower the resistance, the higher the current
circuit a has a resistance of 5 ohms; circuit c is in series so has a resistance of 10 ohms; circuit b is in parallel and therefore has a resistance of 2.5 ohms (review your notes on adding resistances in parallel and series); therefore b has the highest current

The big glowy thing is called the sun it is a star in our galaxy and is over 1 million degrees