• When electricity passes through a component, such as a resistor, some of the electrical energy is turned into heat, therefore, increasing its temperature
  • The heat that is produced will dissipate (spread out) into the environment via thermal conduction, convection and radiation

• When electricity passes through a component, there is energy transferred to?heat
• This is due to?collisions?between:
  • Electrons?flowing in the conductor, and
  • The?lattice of atoms?within the metal conductor
• Electricity, in metals, is caused by a?flow of electrons
  • This is called the?current
• Metals are made up of a?lattice?of ions
• As the electrons pass through the metal lattice they?collide?with ions
  • The ions?resist?the flow of the electrons

As electrons flow through the metal, they collide with ions, making them vibrate more

• When the electrons collide, they lose some energy by giving it to the ions, which start to vibrate?more
  • As a result of this, the metal?heats up

• This is used to an advantage to generate heat for appliances such as electric hobs

The heating effect of current can be used for many applications such as electric hobs

• When an electrical current does work against electrical resistance:
  • Electrical energy is?dissipated as thermal energy?in the surroundings
  • The heat that is produced will dissipate via thermal conduction, convection and radiation

• The amount of heat produced depends on two factors:
  • Current:?The greater the current, the more heat that is produced
  • Resistance:?The higher the resistance, the more heat that is produced (for a given current)

• Note that reducing the resistance can cause the current to increase
  • This could actually?increase?the amount of heat produced

• In mechanics, power?P?is defined as the?rate of doing work
  • The potential difference is the?work done per unit charge
  • Current is the?rate of flow of charge
• Therefore, the electrical power is defined as the?rate of change of work done:

• The work done is the energy transferred so the power is the?energy transferred per second?in an electrical component

• The power dissipated (produced) by an electrical device can also be written as

• Using Ohm's Law?V?=?IR?to rearrange for either?V?or?I?and substituting into the power equation, means power can be written in terms of resistance?R

• This means for a given resistor if the current or voltage?doubles?the power will be?four?times as great.
  • Which equation to use will depend on whether the value of current or voltage has been given in the question
• Rearranging the energy and power equation, the energy can be written as:

E?=?VIt

• Where:
  • E?= energy transferred (J)
  • V?= voltage (V)
  • I =?current (A)
  • t?= time (s)

ANSWER:? ?A