# Physics - Recall for Chapter 10: Electrical Circuits

> Source: https://ollybritton.com/notes/a-level/physics/recall-questions/chapter-10-electrical-circuits/ · Updated: 2021-08-03 · Tags: physics, electrical-circuits, school, recall-questions

## Recall Questions
##### State Kirchoff's second law and appreciate that this a consequence of conservation of energy??
Sum of the EMF is equal to the sum of the voltages.

##### What can we say about the current through a component in series.
Same for each compoent.

##### What can we say about the p.d. across parallel branches in a circuit??
It is the same for each branch.

##### How do you find the total EMF from cells connected in series with the same polarity??
Their EMFs are added.

##### How do you calculate the total resistance of resistors in series??
Sum of the individual resistance.

##### How does the total resistance change when a resistor is added in series??
It always increases.

##### How does the total resistance change when a resistor is added in parallel??
It always decreases.

##### What is the effect of connecting two identical resistors in parallel??
REsistance is halved.

##### What is the effect of connecting two identical resistors in series??
Resistance is doubled.

##### What is internal resistance??
The opposition to current created by the charge carriers having to flow through the soruce of EMF.

##### What are the lost volts for a power supply??
The p.d. dropped across the internal resistance.

##### What is the relationship between EMF, terminal p.d. and lost volts??
EMF = terminal p.d. + lost volts

##### How do you find the internal resistance from a graph of terminal p.d. against current??
Negative of the gradient.

##### How do you find the EMF from a graph of terminal p.d. against current??
$y$-intercept.

##### What is a potential divider??
Two or more resistance in series with a fiexed source of EMF.

##### What determines the ratio of the p.d. across the resistors in a potential divider??
It is equal to the ratio of their resistances.

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