Aman Maheshwari

Resistance is the opposition of electrical current flow. Resistance occurs in AC & DC circuits. In addition to Resistance, AC circuits also exhibit Reactance. Reactance is also the opposition to electrical current flow. By its very nature a DC circuit will not exhibit any form of Reactance, therefore opposition to current flow will always be measured in Resistance. Reactance exists in two forms, Capacitive & Inductive. the combination of Reactance & Resistance is called Impedance Impedance can therefore be thought of as the opposition of electrical current flow in a AC circuit. Due to the nature of AC circuits Reactance is always present (even if only in infinitesimal amounts) Any measurement of the opposition of current flow in an AC circuit will always be measured in Impedance. Impedance & Resistance are both measured in Ohms, and are interchangeable in many electrical formulas in practice i.e, Ohms Law. As a simplistic general view, Impedance can be thought of as Resistance in an AC circuit.

A fictitious force arises when a frame of reference is accelerating compared to a non-accelerating frame. For example if you consider a person standing at a bus stop watching an accelerating car, he infers that a force is exerted on the car and it is accelerating. Here there is no problem and the pseudoforce concept is not required But, if the person inside the accelerating car is looking at the person standing at the bus stop, he finds that the person is accelerating with respect to the car, though no force is acting on it. Here, the concept of pseudo force is required to convert the non-inertial frame of reference to an equivalent inertial frame of reference.