Tag: ac vs dc

Questions Related to ac vs dc

Which of the statements is false?
AC: Alternating current
DC: Direct Current 

ac and dc ac vs dc electro-magnetism effects of electric current physics

  1. AC generation is done by a generator

  2. DC generation is done by electrochemical cells

  3. AC generation can be done by electrochemical cells

  4. None

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Correct Option: C
Explanation:

Electrochemical cells produce DC.

AC is generated by a generator.

What is not a characteristic of alternating current?

ac and dc ac vs dc electro-magnetism effects of electric current physics

  1. Periodic in nature

  2. Time period does not change

  3. Maximum positive amplitude is more than maximum negative amplitude

  4. Average value is 0

Show answer
Correct Option: C
Explanation:
Characteristics of alternating current :

1. Periodic in nature
2. Time period does not change
3. Average value is zero.

Why is AC preferred over DC for transmission of electrical power

ac and dc ac vs dc electro-magnetism effects of electric current physics

  1. AC to DC conversion and vice versa is very easy

  2. Transmission losses in AC are lower

  3. AC transmission is unaffected by random phase change

  4. Frequency of AC do not change

Show answer
Correct Option: B
Explanation:

Transmission losses are given as $I^2R$. In AC, voltage transformation to higher(and also lower) values is easier at constant power. So, voltage is increased before transmission reducing current and hence reducing transmission losses.