Pages in this set

Page 1

Preview of page 1
Physics Electrons, waves and photos




Voltage, energy and power
Page 129
Chapter 11

The meaning of voltage

The voltmeter around a power supply will always read the same. This is because the voltmeter
measures the potential difference between two points. The two points will have the start voltage
e.g. 12,…

Page 2

Preview of page 2
Physics Electrons, waves and photos









Voltage and energy

Using the example above:
A 12 V power supply give 12 J of electrical energy to each coulomb of charge that passes
through it. Each coulomb of charge dissipates 8 J of energy as heat in the first resistor and 4 J…

Page 3

Preview of page 3
Physics Electrons, waves and photos












Electrical power
The rate at which energy is transferred is known as power. Power is measured in watts. It is
defined as:

Power = Energy transferred / Time taken

P = W / t

Where P is the power and W is the energy transferred…

Page 4

Preview of page 4
Physics Electrons, waves and photos
















Fuses

A fuse is a device which is fitted in an electric circuit it is usually there to protect the wiring
from excessive currents. If there is an excessive current in the circuit the fuse will blow. This
happens for safety because high currents can…

Page 5

Preview of page 5
Physics Electrons, waves and photos





Power can be calculated by two equations:

Power = Current 2 x Resistance
P = I 2R

Power = Voltage 2 / Resistance
P = V 2 / R

These two equations can be used to calculate power waster as heat!


Calculating energy

Power =…

Page 6

Preview of page 6
Physics Electrons, waves and photos




























Comments

No comments have yet been made

Similar Physics resources:

See all Physics resources »