Magnetism and Orbits Review

Does this represent attraction or repulsion?

• attraction
• repulstion

Which of the following magnetic fields is correct for a single bar magnet?

• 
• 
• 
• 

What creates a magnetic field?

• charged particles that do not move

• moving electric charges

• gravity

• an isolated magnetic pole

What is the relationship between electrical current and magnetic field strength in an electromagnet?

• When current is increased, magnetic field strength increases
• When current is increased the strength of magnetic field decreases
• When the current is decreased, the strenght of the magnetic field is increased.
• There is an "indirect proportion," meaning, if the value of one goes up, the value of the other goes down.

Calculate the magnetic field at a point, P, 5 cm from a wire carrying a current of 20 A to the left.

• 80 mT into the page

• 0.0004 T into the page

• 80 mT out of the page

• 0.0004 T out of the page

Where is the planet moving faster

• Position A to B
• Position B to C
• Position H to I
• Position I to J

Satellite X orbits the Earth with radius R. Satellite Y orbits at radius 4R. Which statement is incorrect?

• The speed of Y is greater than the speed of X

• The time period of Y is greater than the time period of X.

• The potential energy of Y is greater than the potential energy of X.

• The gravitational force acting on Y is less than the gravitational force acting on X.

The gravitational force between two uniform spheres is 3.1 × 10^–9 N when the distance between their centres is 150 mm. If the mass of one sphere is 2.5 kg, what is the mass of the other?

• 0.043 kg

• 0.42 kg

• 2.8 kg

• 4.1 kg

A planet has a radius half the Earth’s radius and a mass a quarter of the Earth’s mass. What is the approximate gravitational field strength on the surface of the planet?

• 1.6 N kg^–1

• 5.0 N kg^–1

• 10 N kg^–1

• 20 N kg^–1