Question

In the figure below, the switch is left in position a for a long time interval and is then quickly thrown to position b. Rank the magnitudes of the voltages across the four circuit elements a short time thereafter from the largest to the smallest.
a.ΔV1200 Ω > ΔVL > 12.0 V > ΔV12.0 Ω
b.ΔVL > ΔV1200 Ω > 12.0 V > ΔV12.0 Ω
c.ΔV1200 Ω > ΔVL = 12.0 V > ΔV12.0 Ω
d.ΔV1200 Ω = ΔVL > 12.0 V > ΔV12.0 Ω

Answer 1

The current through the circuit when switch is left in position a for long time is
           I = 12.0 V / 12.0Ω

             = 1.00A

After switch is thrown to position b,

            Voltage across 12.0Ω resistor is ΔV₁₂ = (1.00A)(12.00Ω)

                                                                       = 12.0 V

            Voltage across 1200Ω resistor is ΔV₁₂₀₀ = (1.00A)(1200Ω)

                                                                       = 1200 V

Since 1200 Ω resistor paralles with 12.0Ω resistor and 2.00H inductor,

                          ΔV₁₂₀₀ =  ΔV₁₂  +  ΔV_L

                          ΔV_L = 1200V - 12.0V

                                  = 1212 V

Therefore correct option is

b)       ΔVL > ΔV1200 Ω > 12.0 V > ΔV12.0 Ω