# Electric field

An electric field is caused by a change in voltage (charge). The higher the voltage the stronger the field.

• Whilst an electric field is caused by a change in voltage (charge), a magnetic field is caused when electric current flows. The greater the current the stronger the magnetic field.
• An electromagnetic wave is the result of the interaction of an electric and magnetic field. An electric field induces a magnetic field and a magnetic field induces an electric field.
• An electromagnetic wave can be induced when either the charge of an electric field changes or when the current of a magnetic field changes or when they both change together.
• The waveform, wavelength and frequency of an electromagnetic wave result from the rapid periodic succession of transitions between the electrical and magnetic components and the forward propagation of the wave through space.
• When electric and magnetic fields form electromagnetic waves they oscillate at right angles to one another.
• The direction of propagation of an electromagnetic wave is at a right angle to the electric and magnetic fields.
• The velocity at which electromagnetic waves propagate in a vacuum is the speed of light which is 299,792 kilometres per second.
• Once an electromagnetic wave propagates outward it cannot be deflected by an external electric or magnetic field.
• An electromagnetic wave does not need a medium to propagate through because the only thing that is waving/oscillating is the value of the electric and magnetic fields.
• Electric charge is the physical property of matter that causes it to experience a force when placed in an electromagnetic field.
• An electric charge can be positive or negative (commonly carried by protons and electrons respectively).
• Like charges repel each other and unlike charges attract each other.
• An object with an absence of net charge is referred to as neutral.
• If two objects with the same charge are brought towards each other the force produced will be repulsive and it will push them apart.
• If two objects with opposite charges are brought towards each other the force will be attractive and it will pull them towards each other.

An electric field is created by a change in voltage (charge). The higher the voltage the stronger the field.

• Whilst an electric field is created by a change in voltage (charge), a magnetic field is created when electric current flows. The greater the current the stronger the magnetic field.
• An electromagnetic wave is the result of the interaction of an electric and magnetic field because an electric field induces a magnetic field and a magnetic field induces an electric field.
• An electromagnetic wave can be induced when either the charge of an electric field changes or when the current of a magnetic field changes or when they both change together.
• The waveform, wavelength and frequency of an electromagnetic wave result from the rapid periodic succession of transitions between the electrical and magnetic components and the forward propagation of the wave through space.
• When electric and magnetic fields come into contact to form electromagnetic waves they oscillate at right angles to one another.
• The direction of propagation of an electromagnetic wave is at right angles to the electric and magnetic fields.
• The velocity at which electromagnetic waves propagate in a vacuum is the speed of light which is 300,000 metres per second.
• Once an electromagnetic wave propagates outward it cannot be deflected by an external electric or magnetic field.
• The reason an electromagnetic wave does not need a medium to propagate through is that the only thing that is waving/oscillating is the value of the electric and magnetic fields.