Anasa spacecraft measures the rate r of at which atmospheric pressure on mars decreases with altitude. the result at a certain altitude is: =r0.0421·kpakm−1 convert r to ·jcm−4 .

this is simple question of conversion of unit But as we can see here that one is in kpa or kilo pascal which is a unit of pressure while another is in joule which is unit of energy but if we do the dimension matching we could see that 1pa = 1J/m^3 and 0.0421kpa/km=0.0421pa/m now putting above equation as substitution 0.0421pa/m=0.0421J/m^4 100 cm = 1 m putting it we get R= 4.21Ă—10^-10 J/cm^4

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

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