Fields Flashcards
What does gravity, magnetic fields or electric fields affect?
Gravity affects masses
Magnetic fields affect magnetic materials and currents in conductors
Electric fields affect charged particles
Draw a magnetic field on a magnet
What does the density of field lines represent
Field strength
Draw electric fields
Draw the gravity around the planet
Strength of gravitational field on earth’s surface
9.81 N/kg
Field strength def
Newtons per thing affected
Gravitational field strength (g) unit
N/kg
Electric field strength (E) unit
N/C
Magnetic field strength (B) unit
N/magneticness
Draw the gravitational fields between two masses
Graph of gravity against radius
What’s X?
Gravitational Potential Energy def
The energy of an object due to its position in a gravitational field
What is gravitational potential
The work done per unit mass to move a small object from infinity (where GPE is zero) to that point.
What are equipotentials
- Surfaces of constant potential
- this means that no work needs to be done to move along an equipotential surface
- on a planet, the further away from the surface, the weaker the gravitational field. This means that, further away from the earth, the equipotentials for equal increases in potentials are spaced further apart.
Draw the equipotentials around the earth
What is a potential gradient at a point in a gravitational field
The change of potential per meter at that point
- near the earths surface, the potential changes by 9.8J/kg for every meter of height gained. So the potential gradient near the surface of the earth is constant and equal to 9.8J/Kg / m
What symbol is used to represent gravitational potential in equations
V
Does it take energy to move between equipotentials?
Yes because moving between equipotentials means a change in energy, which means work must be done.
Equation linking work done to move equipotentials, mass of object and change in potential
What is escape velocity
How fast you need to be travelling to escape a planets gravity
What does escape velocity depend on?
Gravitational potential at the point in the field the object is at (normally at the surface)
Equation for escape velocity
How do we get an object into orbit?
Equation for a planets time period (M= mass of sun)
Equation for the velocity of a satellite in orbit due to the force of gravity
Equation for the kinetic energy of a satellite in orbit due to the force of gravity
Show how a satellites kinetic energy is half the magnitude of its potential energy
Equation for the total energy of a satellite in orbit due to the force of gravity
Gravitational potential energy equation
