How to i calculate total resistance in a circuit?

Total resistance in a circuit depends on whether the resistors are in series or parallel since this determines which equation is to be used.In series, resistors are essentially lined up next to each other so the total is simple since it is just the sum of the resistors resistance in ohms.e.g. if a circuit has one 10ohm, one 45ohm and one 235ohm resistor in it, all three of which are in series, the total resistance is (10+45+235)ohm = 290ohmsIn parallel each resistor is on its own path for the electricity to follow and as a result the equation is not quite the same, we use the equation: 1/Rtotal = 1/R1 + 1/R+ 1/R..etce.g. a circuit has 3 resistors all in parallel. Their resistances are 25ohm, 5ohm and 100ohm respectivley, what is the total resistance of the circuit?1/Rt = 1/25 + 1/5 + 1/1001/R= 4/100 + 20/100 + 1/1001/R= 25/100100 = 25RtR= 4ohmsoften the answer will be a fraction when calculating a parallel due to the fractions involved in the total calculation however i used a simpler calculation for the example to demonstrate the equation's use

MK
Answered by Matthew K. Physics tutor

17715 Views

See similar Physics GCSE tutors

Related Physics GCSE answers

All answers ▸

Kinetic theory describes the movement of particles in three states of matter. If a cube of ice is put in a tin with a tight fitting lid and continuously heated, why does the lid explode off?


Why is the car moving if the unbalanced force is zero?


What is polarized light?


Waves on the surface of water are transverse waves. State one other example of a transverse wave.


We're here to help

contact us iconContact ustelephone icon+44 (0) 203 773 6020
Facebook logoInstagram logoLinkedIn logo

MyTutor is part of the IXL family of brands:

© 2025 by IXL Learning