2 resistors of resistances 150 ohms and 5000 ohms respectively are in series with each other. They both are also in parallel with a 1000 ohm resistor. What is the total resistance?
Firstly, you should start by working out the total resistance for the 150 ohm and 5000 ohm resistors which are in series: -In series the total resistance is given as the sum of the resistance of each individual resistor (RT=R1+R2+R3...). -Therefore the total resistance of the 150 ohm and 5000 ohm resistors is 5150 ohms (150+5000=5150) Imagine this total resistance of the resisitors in series (5150 ohms) being a resistor that replaces both the 150 ohm and 5000 ohm resistors. Now try working out the total resistance in parallel: -In parallel the reciprocal of the total resistance is given as the sum of the reciprocal of resistance for each individual resistor (1/RT = 1/R1 + 1/R2 + 1/R3 ...) -Therefore the reciprocal of the total resistance is 1/5150 + 1/1000 = 123/103000. So to obtain the total resistance divide 1 by this value (as it is a reciprocal) to get a resitance of 103000/123 ohms which is equivalent to 837.4 ohms (4 s.f.)
Related Physics A Level answers
All answers ▸What are the SUVAT equations and how can I remember them?
A car of mass m travelling with a velocity v comes to rest over a distance d in time t. The constant frictional force acting on the car while it is braking is found using:
Discuss how the graph of orbital velocities in rotational galaxies against distance from the galactic centre implies the existence of dark matter.
Why is it important that the baryon and lepton numbers of an interaction are conserved?