Give one reason why an electromagnet would be used rather than a permanent magnet. Flashcards
an electromagnet can be switched off or an electromagnet is stronger
An atom has a small, positively-charged nucleus surrounded by orbiting negatively-charged electrons. The electrons are arranged at different distances from the nucleus (different energy levels).
Atoms are very small and have a radius of about 1 × 10-10 metres.
The radius of a nucleus is less than \frac{1}{10,000}
10,000
1
of the radius of an atom but most of the mass is concentrated in the nucleus.
Electrons are arranged at different distances from the nucleus. What are these distances known as?
Energy levels
There are three different sub-atomic particles; each has a different charge
Protons are positively charged.
Neutrons have no charge.
Electrons are negatively charged.
The overall charge of an atom is neutral (no charge).
Protons are found in the nucleus. They have a relative charge of +1.
An element’s atomic number is the number of protons it possesses. This means that all atoms of the same element have the same number of protons.
Electrons are found in fixed orbits around the nucleus. They have a relative charge of −1.
Which of the following particles has a relative charge of +1?
Proton
Neutrons are found in the nucleus. They have a relative charge of 0.
Atoms also have no overall electric charge as the number of electrons equals the number of protons.
What is the overall charge of an atom?
0
Fill in the charges of the different sub-atomic particles:
1 Proton = +1 2 Neutron = 0 3 Electron = −1
Magnetism
ebi: find key words from the question in the senecca area instead
Magnetism describes the ability of magnets to attract and repel other magnets without touching them.
Magnets have a north pole (N) and south pole (S). If two magnets are close enough to each other, then the south pole of one magnet will attract the north pole of the other magnet.
What is the term given to the ability of magnets to attract and repel other magnets without touching them?
Magnetism
If one magnet is turned so that both south poles (or both north poles) are close together, then the magnets will repel each other.
Opposite poles on a magnet attract.
Like poles on a magnet repel.
These are both examples of non-contact forces.
What are the names given to the two poles on a magnet?
North pole
South pole
The forces between magnets (magnetic forces) are caused by invisible magnetic fields.
A magnetic field is the area around a magnet where another magnet or magnetic material (iron, nickel, cobalt and steel) feels a force.
What type of force causes magnets to attract and repel one anoth
Non-contact forces
The strength of a magnetic field depends on the distance from the magnet. The magnetic field is strongest at the magnet’s poles.
Where is a magnetic field strongest?
At the poles
Electromangentic Waves
Electromagnetic waves are transverse waves that travel at the same speed in a vacuum. To simplify things, we assume that the speed of EM waves in air is the same as that in a vacuum.
There is a continuous spectrum of EM waves. EM waves transfer energy from the source of the wave to an absorber of the wave and this depends on two factors:
Frequency.
Wavelength.
What type of wave are electromagnetic waves?
Transverse
Wave energy increases with frequency and decreases with wavelength.
Therefore waves with the lowest frequency have the greatest wavelength and waves with the greatest frequency have the shortest wavelength.
Give the two factors that influence the EM spectrum:
Wavelength
Frequency
The EM spectrum can be split into seven types of wave (in order of highest frequency to lowest frequency):
Gamma. X-ray. Ultraviolet (UV). Visible. Infrared. Microwave. Radio waves.
If Gamma rays have the highest frequency in the EM spectrum, what is their wavelength relative to the rest of the spectrum?
the shortest wavelength
Give two types of wave in the electromagnetic spectrum:
Gamma
X-ray
Electromagnetic spectrum
Gamma rays carry the most energy of all electromagnetic waves.
They are used in medical imaging and therapy, astronomy, sterilisation and food preservation.
A risk of gamma rays are that they are extremely penetrating and damaging to living tissues and cells.
Two uses of gamma rays:
Steralisation
astronomy
X-rays carry the second most energy of all the waves in the electromagnetic spectrum.
Low-energy X-rays are used for medical and industrial imaging and high-energy X-rays are used to treat cancer. They are also used for security purposes to detect weapons in airports.
Why are gamma rays dangerous?
They penetrate and dammage living cells
X-rays are dangerous because they are highly ionising which can damage body cells, even in low doses. Exposure to X-rays should always be kept to a minimum and people should use materials (e.g. metals or lead) to protect themselves.
Which of these are uses of X-rays?
treating cancer
medical imaging
Ultraviolet light is found between X-rays and visible light in the electromagnetic spectrum.
It is used in medical and forensic photography, air purification, disinfection and medical therapy. UV light can also be used to detect fake bank notes.
Exposure to too much ultraviolet light can cause skin burns, skin cancer and cataract formations in the eye.
What two types of EM waves is Ultraviolet light found between in the EM spectr
X-rays
visible light
Visible light is in the middle of the EM spectrum. We use visible light to see the world around us.
Traditionally, we say that there are seven colours of light in the spectrum - red, orange, yellow, green, blue, indigo and violet.
Infra-red radiation is the next wave in the electromagnetic spectrum.
It is used in TV controls and for security purposes, such as in intruder alarms by detecting body heat.
Infra-red radiation can cause serious skin burns if emitted from high-intensity sources.
Microwaves are the 6th type of wave in the electromagnetic spectrum.
Microwaves are used in satellite communications, transmitting signals between mobile phones and for heating up water to cook food.
Because humans are largely made up of water, exposure to microwaves could have a harmful effect. Safety precautions can be used to help reduce the impact of microwaves. Protective shielding is installed on microwave ovens to prevent exposure.
Radio waves are the lowest frequency waves in the EM spectrum. They are used for radio and TV communications.
At high intensities, radio waves can cause internal heating of living tissue with potentially harmful effects.
Give three types of wave in the electromagnetic spectrum:
Radio
Microwave
Gamma
