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Electric Current MCQ - Practice Questions with Answers

Edited By admin | Updated on Sep 25, 2023 25:23 PM | #NEET

Quick Facts

  • 20 Questions around this concept.

Solve by difficulty

Conventional current will flow from

The average value of a sinusoidal A.C. current over one cycle is

Concepts Covered - 1

Current
  • Definition: Electric current is defined as the rate of flow of electric charge through any cross-section.

 

i.e If a charge of ΔQ flows through an area for time Δt then
1. average electric current through the area is defined as

i¯=ΔQΔt

2. The instantaneous current at any time t is given by

i=limΔt0ΔQΔt=dQdt


And If the flow is uniform then Current

I=Qt


If a current I flows through an area for time t then, total charge flowing is

Q=Idt
 

  • The direction of current:-

As Current is the rate of flow of charge, Charge can be +ve or -Ve.

 The direction of flow of positive charge is considered as the conventional direction of current .

Or the direction opposite to the direction of flow of negative charge is considered as the conventional direction of the current .

 

  • current flows through a circuit only if the circuit is closed

For a closed circuit  

  1. Conventional current: Positive terminal to negative terminal

  2. Electron current: Negative terminal to Positive terminal

  •  Current can be added algebraically.

  •  Current is a tensor quantity ( if in options tensor is not given take current as scalar quantity)
  • Unit of Electric Current: The unit of electric current is Ampere or A.

The current is said to be 1 ampere when 1 coulomb of charge flows through any cross-section in every second. 

  • Calculating current in different situation-

  1. When charge is performing translatory motion

  • - If n particles each having charge q pass a given area in time t

    i=nqt

    2. When charge is performing rotatory motion

    If a point charge q is moving in a circle of radius r
    With Velocity V (frequency ν, angular speed lomega and time period T )

    Then

    i=qtqT=qν=qV2πr=qw2π
     

  • Types of current

  1. Alternating current

  • Magnitude and direction both varies with time.

  • Shows heating effect only.

  • Its  symbol 

  1. Direct current

  • No change in magnitude and direction with time. 

  • Shows heating effect , chemical effect and magnetic effect of current.

  • It's a symbol

 

  • Current independent of Area-

Current does not change with change in cross-sectional Here i1=i2=i3

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