In the given circuit the current flowing through the resisitance $20$ $\mathrm{ohms}$ is $0.3$ $\mathrm{ampere}$ while the ammeter reads $0.8$ $\mathrm{ampere}.$ What is the value of $R_1$? ................ $\mathrm{ohm}$
  • A$30$ 
  • B$40$ 
  • C$50$ 
  • D$60$ 
Medium
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