1 markSection A

(a) What are geothermal energy hot-spots?

Magnetic Effects of Electric Current

Alternating Current (AC) and Direct Current (DC)

Official Answer

An important advantage of using Alternating Current (AC) over Direct Current (DC) is that electric power can be transmitted over long distances without much loss of energy.

transmitted over long distanceswithout much loss of energylow power lossstepped upstepped down

Marking Scheme

1Stating that AC can be transmitted over long distances: 0.5 mark
2Stating that it occurs with minimal loss of energy/power: 0.5 mark

Hint

Think about how electricity is transported from power plants to distant cities with minimal power loss.

Quick Oral Answer

The main advantage of AC over DC is that AC can be transmitted over very long distances with minimal energy loss because its voltage can be easily stepped up and down using transformers.

Analysis & Explanation

Alternating current (AC) can be easily stepped up to high voltages using transformers for transmission. High-voltage transmission significantly reduces the current ( $I$ ) flowing through the transmission lines, which exponentially decreases the power loss due to Joule heating ( $I^2R$ ). Once the power reaches its destination, it can be stepped down to safe, usable voltages for domestic consumption. Direct current (DC) cannot be stepped up or down easily with high efficiency, resulting in substantial energy losses over long distances.

Common Mistakes

1Stating that AC is safer than DC (AC is actually more dangerous at similar voltages).
2Confusing the direction of current flow with transmission efficiency.

Interesting Facts

The 'War of the Currents' in the late 1880s was a series of events surrounding the introduction of competing electric power transmission systems. Thomas Edison promoted Direct Current (DC), while Nikola Tesla and George Westinghouse championed Alternating Current (AC). AC ultimately won because of its superior long-distance transmission efficiency.

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Frequently Asked Questions

How many marks does this question carry in CBSE Class 10 Science 2020?

This question carries 1 mark in the CBSE Class 10 Science 2020 examination.

Which chapter does this question come from in Science?

This question is from the chapter "Magnetic Effects of Electric Current" in the CBSE Class 10 Science syllabus.

What topic does this question cover in Science?

This question covers the topic "Alternating Current (AC) and Direct Current (DC)" from CBSE Class 10 Science.

What type of question is this in the CBSE Class 10 Science 2020 paper?

This question appears in Section A in the CBSE Class 10 Science 2020 paper.