Chapter 10 - Electrical Circuits

Question 1

Kirchhoff’s second law

Answer 1

total emf= total volts around a closed loop

Question 2

Current in a series circuit

Answer 2

Current is the same everywhere.
If there is only 1 emf, then the voltage is shared and you simply add the together.
If there are more than 1 emfs, you have to find the sum of the emfs. BUT!!! If the emfs (cells) are arranged in opposing polarities, then you have to take them away.

Question 3

In parallel circuits, explain current to resistance relationship

Answer 3

The greater the resistance, the lower the current. It allows less current to pass.

Question 4

In parallel circuits, what is the pd of each loop

Answer 4

The pd of each loop is equal to the emf.

Question 5

Series circuit resistance

Answer 5

R total = R1 + R2…

Question 6

Parallel circuit resistance

Answer 6

1/ R total = 1/ R1 + 1/ R2 …
The total resistance here actually drops here.
By adding a new branch, you create a new way that the current can flow. Therefore, you increase the cross sectional area, and hence lowering the resistance,

Question 7

Deriving the equation for total resistance in a parallel circuit

Answer 7

I tot = I1 + I2 …
R = 1/ V …
V = IR, so I/V = 1/R
so it becomes, 1/R= 1/R1 + 1/R2.

Question 8

how do you know if a component follows Ohm’s Law

Answer 8

It creates a straight line and goes through the origin.
The current is proportional to the voltage.
As long as the temperature remains constant.

Question 9

Define EMF

Answer 9

The energy transferred from source to electrical energy per unit of charge.

Question 10

Kirchhoff’s first law

Answer 10

The sum of the current into a node has to be equal to the sum of the current leaving the node.

Question 11

Why is it better to use electrical machinery?

Answer 11

The data can be given or fed into a computer

You can get automatic records.