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Power Transmission
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Power Transmission
Recommended for Class 10
Power Transmission
Electrical energy is transmitted over long distances through power lines.
A major problem is energy loss due to resistance in the transmission wires.
Power Loss
Heating loss is:
**Ploss = I²R**
This equation shows that transmission loss depends strongly on current.
Why High Voltage Is Used
For transmitted power:
**P = VI**
If power `P` is fixed, increasing voltage allows current to decrease.
Lower current greatly reduces:
I²R losses
Transmission Process
At a power station:
step-up transformer → high voltage, lower current
Near consumers:
step-down transformers → safer/useful lower voltages
Example
Suppose power must be transmitted.
If current is reduced to half:
P_loss ∝ I²
so loss becomes:
**(12)² = 14**
of the original loss.
Why Not Eliminate Resistance?
Real transmission cables have finite resistance.
Engineering aims to reduce losses using:
high transmission voltage; suitable conductors; * appropriate cable dimensions.
Power Transmission — Advanced
Common Mistakes
Common Mistakes
- Mistake
High voltage does not reduce transmitted power automatically.
- Mistake
It allows the same power to be carried at lower current.
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Practice
PQ
Q1. State wire-loss formula.
PQ
Q2. Why does high voltage reduce losses?
PQ
Q3. If current halves, what happens to loss?
PQ
Q4. What does step-up transformer do at station?
PQ
Q5. Why step down near users?
Exam Practice
EQ
Q1. Explain why transmission wires lose energy.
EQ
Q2. Derive why high voltage is useful using `P=VI`.
EQ
Q3. Explain `I²R` loss.
EQ
Q4. Describe roles of step-up and step-down transformers.
EQ
Q5. Calculate loss change if current becomes one third.
School-standard facts for Matric and Intermediate. Original explanations — not copied from textbooks.