A circuit connected to an ac source of emf e = e 0 sin ⁡ 100 t with t in seconds, gives a phase…

A circuit connected to an ac source of emf e=e0sin100t with t in seconds, gives a phase difference of π4 between the emf  e and current i . Which of the following circuits will exhibit this?
  1. RC circuit with R=1 kΩ and C=1 μF
  2. RL circuit with R=1  kΩ and L=1 mH
  3. RL circuit with R=1  kΩ and L=10 mH
  4. RC circuit with R=1 kΩ and C=10 μF

Solution

ω=100 rad/sec 

phase difference between e and i is given by 

tanθ=XR           θ=π4

so   tanθ=tanπ4=1

in case of RL circuit  X=XL=ωL

And in case of RC circuit  X=Xc=1ωc

For option A: R=1000 Ω and

             XC=1ωC=11001×10-6=10000 Ω
              tanθ=XCR1
For option B: R=103 Ω and

                        XL=Lω=10-3100=0.1 Ω

                       tanθ=XLR1
For option  C:R=1000 Ω and

                   XL=ωL=10010=1000 Ω
                    tanθ=XLR1
For optionD:R=1 kΩ=1000 Ω and

                XC=1ωC=110010×10-6=1000 Ω
               tanθ=XCR=1;θ=45o

Asked in: JEE Main 2019 (08 Apr Shift 2)

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