A cell of emf E and internal resistance r is connected to external resistance `R_1 and R_2` and a perfect ammeter. The current in the circuit is measured in four different situations.
without any external resistance in the circuit
with resistance `R _1` only
with `R_1` and `R_2` in parallel combination
with `R_1` and `R_2` in series combination
the currents measured in the four cases are 0.42 A, 1.05A, 1.4A adn 4.2 A, but not necessarily in that order. Identify the currents corresponding to the four case mentioned above.