Chapter 14 - Electrical Circuits

Question 1

What is the equation for power in an electrical circuit?

Answer 1

Power = Current x Potential Difference or P = Potential Difference^2 x Resistance

Question 2

What is Kirchoff’s First Law?

Answer 2

At a circuit junction, the total sum of the current flowing into the circuit is equal to the total sum of the current flowing out of the junction

Question 3

What is Kirchoff’s Second Law?

Answer 3

In a closed circuit, the sum of the potential differences is equal to the sum of the electromotive forces

Question 4

How would you interpret Kirchoff’s Second Law in a parallel circuit?

Answer 4

You would have to consider each branch of the parallel circuit as an individual series circuit with the same power supply. One thing to remember is that the sum of the potential differences is going to be equal to the emf in each of these branches

Question 5

When cells are connected in parallel in a battery, what is the overall emf?

Answer 5

The sum of the emfs of the singular cells

Question 6

Why is it not advisable to connect cells together in parallel and what should one do instead?

Answer 6

As one will attempt to force current back through the other, which is damaging for it. It is better to just buy a bigger battery than to connect the cells together in parallel

Question 7

What is internal resistance?

Answer 7

The resistance inside of power supplies in real life that causes the transfer of thermal energy within them

Question 8

How can a battery be represented on a circuit diagram?

Answer 8

As a cell with a separate fixed resistor attached to it

Question 9

What equation for emf can you use to plot a graph and where can you find each of the variables?

Answer 9

Voltage = emf + (Current x - Internal Resistance). When plotting this with current on the x and potential difference on the y axis, the y intercept would be emf and the gradient the negative equivalence of the internal resistance