Fields

Question 1

What does gravity, magnetic fields or electric fields affect?

Answer 1

Gravity affects masses
Magnetic fields affect magnetic materials and currents in conductors
Electric fields affect charged particles

Question 2

Draw a magnetic field on a magnet

Answer 2

Question 3

What does the density of field lines represent

Answer 3

Field strength

Question 4

Draw electric fields

Answer 4

Question 5

Draw the gravity around the planet

Answer 5

Question 6

Strength of gravitational field on earth’s surface

Answer 6

9.81 N/kg

Question 7

Field strength def

Answer 7

Newtons per thing affected

Question 8

Gravitational field strength (g) unit

Answer 8

N/kg

Question 9

Electric field strength (E) unit

Answer 9

N/C

Question 10

Magnetic field strength (B) unit

Answer 10

N/magneticness

Question 11

Draw the gravitational fields between two masses

Answer 11

Question 12

Graph of gravity against radius

Answer 12

Question 13

What’s X?

Answer 13

Question 14

Gravitational Potential Energy def

Answer 14

The energy of an object due to its position in a gravitational field

Question 15

What is gravitational potential

Answer 15

The work done per unit mass to move a small object from infinity (where GPE is zero) to that point.

Question 16

What are equipotentials

Answer 16

• 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.

Question 17

Draw the equipotentials around the earth

Answer 17

Question 18

What is a potential gradient at a point in a gravitational field

Answer 18

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

Question 19

What symbol is used to represent gravitational potential in equations

Answer 19

V

Question 20

Does it take energy to move between equipotentials?

Answer 20

Yes because moving between equipotentials means a change in energy, which means work must be done.

Question 21

Equation linking work done to move equipotentials, mass of object and change in potential

Answer 21

Question 22

What is escape velocity

Answer 22

How fast you need to be travelling to escape a planets gravity

Question 23

What does escape velocity depend on?

Answer 23

Gravitational potential at the point in the field the object is at (normally at the surface)

Question 24

Equation for escape velocity

Answer 24

Question 25

How do we get an object into orbit?

Answer 25

Question 26

Equation for a planets time period (M= mass of sun)

Answer 26

Question 27

Equation for the velocity of a satellite in orbit due to the force of gravity

Answer 27

Question 28

Equation for the kinetic energy of a satellite in orbit due to the force of gravity

Answer 28

Question 29

Show how a satellites kinetic energy is half the magnitude of its potential energy

Answer 29

Question 30

Equation for the total energy of a satellite in orbit due to the force of gravity

Answer 30

Question 31

Gravitational potential energy equation

Answer 31