# The terminal voltage of an ideal DC voltage source is 12 V when connected to a 2 W resistive load. When the load is disconnected, the terminal voltage rises to 12.4V. What are the values of source voltage, Vs, and internal resistance Rs of the source?

The terminal voltage of an ideal DC voltage source is 12 V when connected to a 2 W resistive load. When the load is disconnected, the terminal voltage rises to 12.4V. What are the values of source voltage, V

_{s,}and internal resistance R_{s}of the source?### Right Answer is:

V_{s} =12.4 V, R_{s} = 2.4 Ω

#### SOLUTION

When the load is disconnected i.e. open-circuited, the terminal voltage is 12.4 V. Therefore, the source voltage is 12.4 as shown in figure

And, when the resistive load of 2 W, the** terminal voltage seen is 12 V a**s shown in fig

Therefore internal resistance R_{s}

V_{oc} − V_{s} = I × R_{s}

P = V.I

2 = 12 × I

I = 1/6A

12.4 − 12 = R_{s}/6

**R _{s }= 2.4 Ω**