Question

What resistance should a resistor be to be used as a part of a voltage divider along a 1.2 kΩ resistor? The potential difference across the 1.2 kΩ resistor is to be 2.2 V when the supply is 12 V​

Answer 1

Solution :-

As per the given data ,

◕ R 1 = 1.2 kΩ

◕ R 2 = unknown

◕ V 1 = 2.2 V

◕ Supply voltage ( V ) = 12 V

We know that ,

➜ V =  V 1 + V 2

On re arranging ,

➜ V 2 = V - V2

➜ V 2 = 12 - 2.2

➜ V 2 = 9.8 V

As both the resistors are connected in series combination with each other the current flowing through both the resistors is the same

➜  I = V 1 / R 1

➜  I = V 2 / R 2

Hence ,

➜  V 1 / R 1 = V 2 / R 2

On rearranging ,

➜  R 2 = V2 X R 1 / V 1

➜  R 2 = 9.8 x 1.2 / 2.2

➜  R 2 = 11.76 / 2.2

➜  R 2 = 5.34 kΩ

The resistance of the unknown resistor  is 5.34 kΩ