1. A point charge is moved between two parallel plates separated by a distance of $5cm$. The potential difference between the points is $50V$.

What is the average electric field E?

2. A conductor carrying electric current out of the plane of the paper is placed between two magnets as shown in the diagram.

At which location is the magnitude of the resultant magnetic field strength largest due to the conductor and the magnets?

3. Two objects A and B are separated by a distance $r$. The mass of A is much larger than that of B.

Which of the following is correct about magnitude and direction of the gravitational force exerted by A on B compared to that exerted by B on A?

4. Two charges separated by a distance $r$ are placed in a medium with permittivity $ϵ$. The charges are then moved to air so that they have the same force between them as that in the medium.

5. Planet $X$ has radius $R$ and density $\rho$. The gravitational field strength at the surface of Planet $X$ is $g$.

What is the ratio of the gravitational field strength at the surface of planet Y, which has radius 0.25$R$ and density 3$\rho$, to that at the surface of Planet X?

6. Satellites $A$ and $B$ orbit the same planet of mass $M$. Satellite $A$ has a mass of $3m$ and it is located at a height of $R$ from the surface of the planet. Satellite $B$ has a mass of $m$ and it is located at a height of 2$R$ from the surface of the planet.

What is the ratio of the centripetal force acting on $A$ to the centripetal force acting on $B$?

7. A positive and a negative charge of equal magnitude are located on the same horizontal line.

What is the direction of the net electric field at the point marked X, equidistant from the two charges?

8. In the following diagram, the size of the charges is small compared to the distance R.

What is the direction of the force on the charge in the center?

9. A satellite is in a circular orbit of radius $R$ around a planet of mass $M$. Which of the following graphs represents the relationship between the centripetal acceleration of the satellite and its orbital radius?

A.				B.
C.				D.

10. A current-carrying wire is at right angles to a uniform magnetic field. The magnetic force per unit length on the wire is F/L. The length of the wire, the magnitude of the magnetic field strength, and the current of the wire are all doubled. Which of the following is the magnetic force per unit length on the wire after these changes?

11. Estimate the speed of an alpha particle that has accelerated from rest in a uniform electric field E=50NC^−1 over a distance of 2.0m.

12. Two positive charges of magnitude $2C$ and $8C$ respectively are placed 9cm apart. A third charge is introduced between the two charges as shown below;

At what separation, X, from the 2C charge is the electric field strength equal to zero?

13. A charge of $X$ and a charge of $20nC$ are held at a fixed distance.

A point where the electric field is zero can only be found in region 1. Which of the following statements is true about the charge on $X$?

14. A beam of electrons enters a uniform electric field, as shown.

What effect does this field have on the horizontal and vertical components of the electrons' velocity?

15. The diagram shows the gravitational field between two masses m1 and m2.

Which of the following is correct?

16. A wire is carrying a current $I$ is placed in a region of uniform magnetic field B1. The magnitude of the magnetic field is $B$, and its direction is into the page. The force acting on the wire is $F$, as shown in the diagram.

The wire, carrying the same current $I$, is now placed with the orientation shown into another region of uniform magnetic field B2. The magnitude of the magnetic field is $B$, and its direction is out of the page.

What is the correct direction and magnitude of the force acting on the wire in field B2?

	Direction	Magnitude
A.		$F$
B.		$F$
C.		$F\sin \theta$
D.		$F\sin \theta$

17. A source of radiation is near a magnetic field that is directed into the page. A sheet of paper is placed in the path of the radiation before it enters the magnetic field.

The gamma radiation is not deflected when entering the magnetic field. Which of the following is correct about the other type of radiation that penetrates the paper sheet and the direction of its deflected path in the magnetic field?

18. Four fixed charged point particles are at the vertices of a rectangle. Which arrow represents the net electric field at the center of the rectangle?

19. A proton and another object with charge +e exert electrical and gravitational forces on one another. To the nearest order of magnitude, what mass must the object have to be so that the net force acting on it is zero?

20. An electron enters a region of magnetic field with a velocity as shown in the diagram. The path followed by the electron is shown by the dotted line. What is the direction of the magnetic field in this region?

21. Which of the following correctly lists the fundamental forces in decreasing order of strength?

22. Two sections of current-carrying wires, $X$ and $Y$, that lie in the plane of the paper, are shown below. The arrow in wire $X$ shows the direction of conventional current. Which response gives possible directions of current in wire $Y$ and electromagnetic force acting on $Y$?

23. A satellite of mass $m$ is in an orbit at a height $h$ from the surface of a planet of mass $M$. The centripetal force acting on the satellite is $F$ and the linear speed is $v$.

What is the new centripetal force and linear orbital speed when it is moved to a new orbit at $2h$ from the surface of the planet?

24. An object of mass $m$ and charge $q$ is dropped vertically between two parallel plates, $K$ and $L$. A magnetic field $B$ can be created perpendicular to the plane of the paper. The electric field between plates is $E$.

Which of the following is correct about the magnitude of magnetic and electric fields when the object falls vertically at a constant velocity v?

25. Which of the following graphs shows the variation of the gravitational field strength of a planet with distance $r$ from the surface of a planet?

A.			B.
C.			D.