 µ IB | Fields (AHL)

10 quick questions

10 minutes maximum! (can you do it in 5?)

1. Electrical potential Ve is given by the equation:- Which of these is the unit given for Ve?

• A. joule per second
• B. joule per kilogram
• C. coulomb
• D. volt

2. Which of these diagrams correctly shows the electric field pattern around a single negative charge like an electron? 3. Which of these diagrams shows the electric field between 2 identical positive charges? (Only a few key field lines have been shown). 4. At the point directly in the centre of the two positive charges q shown in question 3, the distance from each charge is r.
What is the electric field strength E and the electrical potential Ve?

E Ve
A
zero zero
B
zero
 2kq r
C
 2kq r2
zero
D
 2kq r2
 2kq r

5. Gravitational and electrical fields have 'equipotential surfaces'. These are always..

• A. ..equally spaced.
• B. ..perpendicular to field lines.
• C. ..circular.
• D. ..measured in units of energy.

6. The graph below shows how a quantity (x) varies with distance (r) from an object. In this graph x is inversely proportional to -r.

 x ∝ - 1 r This could be a graph showing....

• A. ..graviational potential with distance r from a planet.
• B. ..electric field strength from a point charge.
• C. ..the kinetic energy with distance r for a body in orbit around a planet.
• D. ..electric potential from a point positive charge.

7. A space ship is projected along the Moon's surface at high speed and then projected into space. It requires an escape velocity of v.

To reach deep space from a moon with no atmosphere, the same mass but four times the radius will require a velocity of: • A. v/4
• B. v/2
• C. 2v
• D. 4v

8. A body of mass m is in orbit at a distance r around a planet of mass M.
The kinetic energy Ek of the body is: 9 & 10. The gravitational potential at the surface of the Moon is 2.8 MJ kg-1. 9. This means that if a 10 kg rock is lifted from the Moon's surface into space:

• A. 28 MJ of energy is released.
• B. 28 MJ of enefy is required.
• C. 0.28 MJ of energy is released.
• D. 0.28 MJ of enefy is required.

10. To calculate the gravitational energy increase for this rock over a small height increase Δr, the formula required is: 