10 minutes maximum! Can you do it in 5?


1. Electrical potential V_{e} is given by the equation:
Which of these is the unit given for V_{e}?
 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 V_{e}? 


E 
V_{e} 
A 
zero 
zero 
B 
zero 

C 

zero 
D 




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.
This could be a graph showing.... 
 A. ..gravitational 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 E_{k}_{} 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 energy is required.
 C. 0.28 MJ of energy is released.
 D. 0.28 MJ of energy is required.


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


