Question

, a variable resistor () and a resistor of fixed resis The figure below shows an electric circuit containing a source of em tance R. The resistor R is immersed in a sealed beaker containing a mass m of water, currently at temperature T When the switch S is closed, current through the circuit causes the resistor in the water to dissipate heat, which is absorbed by the water A stirrer at the bottom of the beaker simply ensures that the temperature is uniform throughout the water at any given moment The apparatus is well-insulated (insulation not shown), and it may be assumed that no heat is lost to the walls or lid of the 1. beaker or to the stirrer. variable resistor, r lid water stirrer (a) Determine the current in the circuit once S is closed. Write your answer in terms of 8, r, and R. (b) How much heat is dissipated by the resistor R in time r?

Answer 1

when switch is closed current in circuit is =

heat dissipated in R in time t = I² t =

)2

with the help of stirrer we can have uniform heating of water and temperature of water will rise uniformly

moreover rotational kinetic energy of stirrer can also heat up the water

as temperature of water increases then molecular have more kinetic energy and they hit the walls of container more rapidly leading to increase in pressure

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