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Question 1

Kirchoff’s Second law?

Answer 1

For two or more components in series, the emf is equal to the sum of the potential differences across all the components.

Question 2

Kirchoff’s First Law?

Answer 2

At any junction in a circuit, the Total current leaving the junction is equal to the total current entering the junction.

Question 3

Potential difference definition?

Answer 3

The potential difference between any two points in a circuit is the energy transfer per coulomb of charge. (Makes sense, when a component has resistance some of the energy stored on the charge carrier must be transferred to the component because the charge carrier must do work to pass through the component so must do work against the restive forces in the component, it’s resistance. So the charge carrier transfers energy to the component which is why as the resistance of a component increases the charge carrier must do more work to pass through the component so more energy is transferred to the component and as electric potential is just an energy well this means more energy must be transferred to the component through work done against resistive forces. So a higher p.d. across the component if the resistance across the component increases.)

Question 4

Why is potential difference the same across parallel branches or components in parallel?

Answer 4

The charge carrier can take either route, either branch. this means if the components in parallel are the same then they have the same resistance so the charge carrier must do the same amount o fowork to pass through each component so deposits the same amount of energy to each component. Sam his true for branches, the charge carriers must transfer all o their energy regardless of which route they take, which branch they take. Therefore the sum of the p.d.s across each component inn a branch must equal the terminal p.d.

Question 5

What is the internal resistance of a source of electricity?

Answer 5

This is due to opposition to the flow of charge. This means electrical energy produced by the source which the charge carrier picks up, to be dissipated/ transferred to the source( cell, battery) due to work needing to be done against their resistive forces( internal resistances.) This leads to a ‘Potential drop’ across the source so the source or cell has ‘lost volts’ due to energy being dissipated in the source.

Question 6

Define Emf?

Answer 6

The electrical energy per unit charge produced by the source in a circuit.

Question 7

What is another way of finding the internal resistance of a cell or source?

Answer 7

Measuring the terminal p.d. for two different values of current. Allows you to set up simultaneous equations where emf cancels out.

Question 8

How is Conservation of energy shown in circuits?

Answer 8

The electrical energy which a charge carrier passing through the source gains will always be equal to the sum of the ‘potential drops’ in the circuit across all the components. So a ‘potential drop’ ( like in an electrical field) requires energy for it to go from zero potential to negative or positive potential.( Work done in moving a unit positive charge from infinity to that point, change in potential requires work done.) So when potential is dropped across a component energy is transferred to it as work must be done to change the potential (in an electric field or circuit.) So as energy must be conserved the amount o energy dropped in potential drops around the circuit components must equal the total electrical energy gained by the charge carrier in the source.