# Physics definitions G485

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• Created by: gillykite
• Created on: 13-03-16 13:25
Electric field strength
The electric field strength at a point is the force per unit charge exerted on a positive charge placed at that point.
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Coulomb's law
Any two point charges exert an electrical force on each other that is proportional to the product of their charges and inversely proportional to the square of their separation.
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Magnetic flux density
The magnetic flux density is 1T when a wire carrying a current of 1A is placed at right angles to the magnetic field and experiences a force of 1N per metre of its length.
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The magnitude of the induced emf is proportional to the rate of change of magnetic flux linkage.
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Lenz's law
Any induced current or emf will be established in a direction so as to produce effects which oppose the change that is producing it.
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Capacitance
The capacitance of a capacitor is the charge stored per unit potential difference across it.
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Work done
The work done is proportional tot the product of potential difference and charge.
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Isotope
Isotopes are nuclei of the same element with a different number of neutrons but the same number of protons.
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Mass defect
The mass defect of a nucleus is equal to the difference between the total mass of the individual, separate nucleons and the mass of the nucleus.
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Binding energy
The minimum energy needed to pull a nucleus apart into its separate nucleons.
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Decay constant
The probability that an individual nucleus will decay per unit time interval.
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Activity
The activity of a radioactive sample is the rate at which nuclei decay or disintegrate.
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Half-life
The half-life of a radioactive isotope is the mean time taken for half of the active sample to decay.
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Intensity
The power per unit cross-sectional area.
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Astronomical unit
The average distance between the Earth and the Sun.
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Light year
The distance travelled by light through a vacuum in one year.
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Arc second
1/3600 degrees
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Parsec
The distance that give a parallax angle of 1 arc second.
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For an infinite, uniform and static universe, the night sky should be bright because of light in all directions from stars.
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## Other cards in this set

### Card 2

#### Front

Any two point charges exert an electrical force on each other that is proportional to the product of their charges and inversely proportional to the square of their separation.

Coulomb's law

### Card 3

#### Front

The magnetic flux density is 1T when a wire carrying a current of 1A is placed at right angles to the magnetic field and experiences a force of 1N per metre of its length.

### Card 4

#### Front

The magnitude of the induced emf is proportional to the rate of change of magnetic flux linkage.

### Card 5

#### Front

Any induced current or emf will be established in a direction so as to produce effects which oppose the change that is producing it.