Current electricity | Introduction to current and types of current | advguruji

Electric Current

It is defined as the rate of flow of positive charge. It has the direction towards the motion of positive charge and direction opposite to the motion of negative charge. It is denoted by I. Its SI unit is ampere(A) or C/s.

It is of two types :-

• Direct current [DC]
• Alternating current [AC]

Direct Current (DC)

The current which has a same direction of flow. It is of two types :

1. fluctuating current

The current whose magnitude changes again and again is called fluctuating current.

2. Steady current or ideal current

The current whose magnitude do not changes with time is called steady current.

Alternating current (AC)

The current which changes its direction of flow periodically.

(In detail, chapter 7)

On the basis of calculation

Current is of two types :

1. Average current [ I = q/t ]

It is defined as the ratio of total charge flow to the total time of flow.

2. Instantaneous current [ I = dq/dt ]

It is defined as the ratio of small change in charge to the small change in time.

Or

Current at an instant of time is called instantaneous current.

Questions for Practice

Q1. A charge of 200 mC flows in 5 seconds in a conductor. Find the average current flowing in the conductor.

Q2. A charge of 420 C flows in 1 minute in a conductor. Find the current flowing in the conductor.

Q3. The current flowing in a conductor is the function of time given by : I = 6t + 1. Find -

1. Current at 8th second in the conductor.

2. Charge flow in the conductor in first 10 seconds (use two different methods)

Here, I(in A) and t(in seconds).

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