Concepts

Class 10
Chapter 13 Class 10 - Magnetic Effects of Electric Current

## What is Direct Current

If current flows only in 1 Direction,

it is called Direct Current

It is denoted by DC or d.c

Here, the positive and negative polarity of current is fixed

Example

The current we get from a cell or a battery is direct current because it always flows in the same direction.

## What is Alternating Current?

Alternating Current reverses direction in equal intervals of time

It is denoted by AC or a.c

Positive Negative Polarity is not fixed and keep on changing

Uses

It is used to transmit current over long distance without much loss of current

Most of power stations in India generate Alternating Current

## Difference between Direct Current and Alternating Current

 Direct Current Alternating Current Meaning Current flows only in one direction Current reverses direction in equal intervals of time Abbreviation D.C. A.C. Change in Polarity There is no change in polarity. It is fixed. There is change in polarity after a fixed interval. It is not fixed. Frequency Frequency of Direct Current is 0 Frequency of Alternating current depends on the country - it is usually 50 Hz or 60 Hz Current Current is of constant magnitude Current varies with time Uses Used in televisions. Used to transmit current over long distances. Component Used in Generator Split Ring is used Commutator is used

## What is Frequency of Alternating Current generated in India?

It is 50 Hz

It means the coil is rotated at a frequency of 50 Revolutions per second

In every revolution, it changes direction from Positive to Negative and then from Negative to Positive

Hence, overall it changes direction 100 times in 1 second (50 positive + 50 Negative)

Hence we can say that

This Alternating Current changes direction every 1/100 seconds

Explanation-

Time in which 100 directions changed = 1 second

Time in which 1 directions changed = 1/100 second

Which Type of Current is Used in Television/Radio Sets

They use Direct Current (D.C. or d.c)

Note - Power supply to television sets is in form of DC

They have a device which convert AC current into DC current

## Questions

Question 2 Page 237 - Name some sources of direct current.

Question 3 Page 237 - Which sources produce alternating current?

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