Question

two identical resistors each of resistance 2 ohm are connected in turn :

I. in series

2.in parallel to a battery of 12V .

3.calculate the ratio of power consumed in the two cases.

please answer immediately. exam is on sunday.

Answer 1

(1) IN SERIES

Total Resistance in Series = R₁ + R₂

                                         = 2 + 2

                                         = 4 Ohm

Potential Difference(V) = 12V

Current(I)= V/R

              =12/4

              =3Ampere

Power = VI

          = 12*3

          =36 Watts

(2) IN PARALLEL

1/R₁ + 1/R₂ = 1/Rₐ (Where Rₐ is the total resistance)

1/2 + 1/2 = 1/Rₐ                                            

2/2 =1/Rₐ

1/1 = 1/Rₐ      

1 Ohm = Rₐ

Voltage (V)= 12Volts

Current(I)= V/R

              = 12 Ampere

Power= VI

         = 12*12

         = 144 Watt

Power in series : Power in Parallel

36 : 144

1 : 4