Question

What physical process is launched with the switching on of the toaster? Why does the current decrease from its initial value and reach another steady value? Choose the best answer from below.

A. When switched on, heating element of the toaster acts as a parallel connection of a resistor and an inductor. This connection reacts to any change of the current with a delay. As the result, current initially increases to a greater value and then reaches the saturated value.

B. When switched on, heating element of the toaster acts as a resistor and converts electrical energy into thermal. However, there are imperfections in the circuit that lead to a loss of energy. As the result, amount of the current that is transformed to thermal energy decreases.

C. When switched on, heating element of the toaster acts as a parallel connection of a resistor and a conductor. This connection reacts to any change of the voltage with a delay. As the result, current initially increases to a greater value and then reaches the saturated value.

D. When switched on, heating element of the toaster acts as a resistor and converts electrical energy into thermal. Resistivity of the element depends on its temperature, so as it heats up, its resistance changes and as so does the current.

Answer 1

As toaster is purely resistive load, so the option A and C are out. Now according to option B there are imperfections in the circuit and imperfections will consume same amount of power for loss, so current will not decrease. For option D, resistivity decrease with temperature as mobility of current carriers increase. So, resistance decrease with increasing temperature. So, option D is most correct option.

In the case of parallel RL circuit current attains it's maximum value after some time. So, current increases from zero to maximum value and stays maximum.