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# 5. Parallel Circuits

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Lecture

In this mini-lecture, we introduce parallel circuits, in which there is more than one path for the current to take through the circuit. As we move through this mini-lecture we consider: (i) that for parallel circuits, the change in voltage across each parallel path is the same and the current I = I1 + I2 + … where I is the current coming directly from the battery and I1, I2, … are the currents of the parallel branches that split off from I; (ii) an example of how to calculate the current directly from the battery when the battery voltage and resistance of resistors across each path are given; and (iii) the equation relating total resistance to the individual resistances in parallel circuits: 1/Rtotal = 1/R1 + 1/R2 + …, where Rtotal = I/V is given by Ohm’s Law and R1, R2, … are the resistances across each parallel path 1, 2, ….

Course

In this course, Professor David Berman (Queen Mary University of London) explores charge, energy, and circuits at a GCSE level. In the first mini-lecture, we look at charges, the force a charge experiences in an electric field, potential energy, potential difference (or ‘voltage’), and energy (or ‘work done’). In the second mini-lecture, we introduce current as the flow of charge and define it mathematically before going through a couple of examples. The third mini-lecture delves into circuits, introducing the concept of circuit diagrams, resistance and resistors, and Ohm’s Law, followed by a few examples. In the fourth mini-lecture, we discuss properties of current, voltage, and resistance in circuits and introduce the series circuit, a circuit with only one path that the current can take. The fifth mini-lecture introduces parallel circuits as circuits in which the current can take more than one path through the circuit, and then goes through an example, concluding with the equation for resistors in parallel.

Lecturer

David Berman is a Professor of Theoretical Physics at Queen Mary. His research interests include string theory and ideas in fundamental theoretical physics, including non-commutative geometry, black holes physics, and quantum gravity. He has contributed to the Radio 4 biography series Great Lives and the In Our Time podcasts, including Great Lives: Richard Feynman (2018), Great Lives: Galileo (2019), In Our Time: Emmy Noether (2019), and In Our Time: Paul Dirac (2020).

#### Cite this Lecture

APA style

Berman, D. (2022, January 12). Introduction to Electricity and Circuits - Parallel Circuits [Video]. MASSOLIT. https://massolit.io/courses/introduction-to-circuits/parallel-circuits

MLA style

Berman, David. "Introduction to Electricity and Circuits – Parallel Circuits." MASSOLIT, uploaded by MASSOLIT, 12 Jan 2022, https://massolit.io/courses/introduction-to-circuits/parallel-circuits