Physics Lectures Practice Session Testing Mode Video No. 17

Testing Mode Video No. 17 Module # 23 Current & Charge Current Electric current I in a conductor is defined by the relation, I = Q / t Where, Q is the net amount of charge that passes through a certain area of cross section of the conductor in time “t”. The current which always flows from positive to the negative potential is usually known as conventional current. The actual current is due to flow of electrons from negative to the positive terminal. The unit of current is ampere. In an electrical circuit, the potential difference across a conductor is directly proportional to the current flowing through it, provided the temperature of the conductor remains the same. Under this condition, the ratio of potential difference V to the current I is constant and is known as resistance R R = V / I The unit of resistance is ohm (Ω): Ohm = 1 volt /1 ampere The resistance of a conductor is one ohm if on applying a potential difference of 1 volt across its ends, a current of 1 am