Question

In given circuit diagram two resistors are connected to a 5 volt supply. Calculate potential difference across the 8 ohm resistor. Third resistor is now connected in parallel with 6 ohm resistor will the potential difference across the 8 ohm resistor the larger smaller or the same as before explain the reason for your answer.​

Answer 1

Given:

V=5 V

R₁=8 ohm

R₂=6 ohm

R₃=R ohm

where R is the resistor connected in the latter part of the question

Solution:

To find the potential difference across 8 ohm resistor we first need to find the net resistance of the system

Rn=R₁+R₂

where R₁=8 ohm

R₂=6 ohm

Rn=8+6

=14 ohm

net current through the circuit is given by

I=V/Rn

=5/14 A

potential difference across 8 ohm resistor is

V₈=I*R₁

=5/14*8

=2.86 V    or   20/7 V

• If we connect a resistor across R₂ (resistor connected is R) then the total resistance of the combination of R₂ and R will decrease

• Due to this decrease in resistance the resistance of the total system will also decrease. If the total resistance decreases then the current through the system will automatically increase due to Ohm's law.

• If current through the system increases then the current through 8 ohm resistor will also increase which will in turn increase the potential difference across it.

• Therefore the new potential difference will be greater than the previous one.

Hope this helps.