Question

RIA visited her aunt house ans observed that all the tube light ans fans in her house were switched on without any need she switched off all the lights and fans which were not in use but was scolded by her aunt for doing so. she then explained her aunt about the need to save electricity . Later ria's aunt promised her that she. she will save electricity now answer the following question

a) why did ria insist on saving electricity?
b) state two ways by which electricity can be saved
c) which values of ria is related in her actions?

Answer 1

a) Ria insist on saving electricity because there is shortage of electricity.
b) Electricity can be saved in 2 ways
Switching off the electric applications when it is not used.
By using natural lights.
c) Responsible citizen.

Answer 2

Answer:

(a) First one is direct current and the second one is alternating current .

(b) Source of DC current is battery and that for alternating current is dynamo motor .

c) Frequency of current used in domestic supply in India is 50 Hz .

(d) 

Alternating Current Direct Current

Amount of energy that can be carried:

Safe to transfer over longer city distances and can provide more power.

Voltage of DC cannot travel very far until it begins to lose energy.

Flow of Electrons:

Electrons keep switching directions - forward and backward.

Electrons move steadily in one direction or 'forward'.

Cause of the direction of flow of electrons:

Rotating magnet along the wire.

Steady magnetism along the wire.

Frequency:

The frequency of alternating current is 50Hz or 60Hz depending upon the country.

The frequency of direct current is zero.

Direction:

It reverses its direction while flowing in a circuit.

It flows in one direction in the circuit.

Current:

It is the current of magnitude varying with time

It is the current of constant magnitude.

Types:

Sinusoidal, Trapezoidal, Triangular, Square.

Pure and pulsating.

Obtained from:

A.C Generator and mains.

Cell or Battery.

(e) AC current is used in transmitting electric power over a long .

Because AC is easy and cheap to transform from one voltage to another using transformers. High voltage means less amperage for the same power, meaning you can do with thinner wires. But high voltage is difficult and dangerous to use. With AC, it's easy to transform 400kV from transmission lines into the 110 or 220V that you can use at home. 

Regards