A conductor of resistance R1 (4ohm) and an electric lamp of resistance R2 are connected to a 12V battery as shown in figure. The net resistance of the circuit is 4/3 ohm. (A) Which physical quantity remains constant in above combination of resistors? (B) Find the total current drawn in the circuit.

Acommercial refrigerator with refrigerant-134a as the working fluid is used to keep the refrigerated space at -35°c by rejecting waste heat to cooling water that enters the condenser at 18°c at a rate of 0.25 kg/s and leaves at 26°c. the refrigerant enters the condenser at 1.2 mpa and 50°c. if the compressor consumes 3.3 kw of power, determine (a) the mass flow rate of the refrigerant, (b) the refrigeration load, (c) the cop, and (d) the minimum power input to the compressor for the same refrigeration load.