Question

A generator at a utility company produces $100A$ of current at $4000V$. The voltage is stepped-up to $240000V$ by a transformer before it is sent on a high voltage transmission line. The current in the transmission line is

• A. $3.67A$
• B. $2.67A$
• C. $1.67A$
• D. $2.40A$

Answer 1

The correct option is C

$1.67A$

Step 1. Given data:

Voltage in the primary coil, $V_P=4000V$

Current in the primary coil, $I_P=100A$

Voltage in the secondary coil, $V_S=240000V$

Current in the secondary coil, $I_S=?$

Step 2. Calculating current in the secondary coil:

For a transformer, assuming no loss of power:

$V_P\times I_P=V_S\times I_S$

$\begin{array}{rcl}& \Rightarrow & 4000x100=240000x{I}_S\\ & \Rightarrow & I_S=\frac{(4000x100)}{240000}\\ \therefore I_S& =& 1.67A\end{array}$

Hence, correct option is (C).