1. 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?

An alpha particle of mass m and charge $q$, is accelerated through a potential difference $V$ into a magnetic field of flux density $B$ that is at right angles to the direction of motion. Which of the sketches below best describes the relationship between the radius of path $r$ and the potential difference of the accelerating field?

2.

A.			B.
C.			D.

3. Two stars of equal mass $M$ are shown in the diagram, distance $d$ apart. A planet is equidistant from the two stars, with distance d/2​ across the midpoint of the line joining the stars as shown.

What is the resultant gravitational field strength at the position of the planet due to the two stars?

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

5. 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.

6. 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?

7. 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?

8. Satellite $A$ of mass $M$ orbits a planet with an orbital speed $v$ and orbital radius $R$. Another satellite $B$ with mass $3M$ orbits the same planet with the same orbital speed.

9. 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?

10. 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 $X$?

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

Which of the following is correct?

12. Which of the following is correct about the gravitational field strength at a point near a planet?

13. The diagram below shows a circuit connected to an iron rod $XY$. The connecting wires are flexible. The rod is placed in a magnetic field directed perpendicularly into the page as shown.

In what direction will the resultant force act on the rod when the current is switched on in the circuit?

14. Planet $A$ has a gravitational field strength $g$ at its surface. Planet $B$ has twice the density and twice the radius of planet $A$.

What is the gravitational field strength at the surface of $B$?

15. A charged particle is moving horizontally when it enters an electric field between two parallel plates. The path followed by the particle when it passes through the plates is shown. Assume gravitational effects to be negligible.

Which statements are correct about the charged particle?

• I. The particle is positively charged.
• II. A magnetic field in a direction into the page could cause the charged particles to move horizontally without deflection.
• III. A magnetic field in a direction out of the page could cause the charged particles to move horizontally without deflection.

16. 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?

17. 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.

18. 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?

19. 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.		$F\sin \theta$

20. 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?

21. The centers of three masses lie on the same line. The centers of the masses are separated as shown.

The net gravitational force on m2​ is zero when the value of $d$ is one third of $x$. What is the ratio m1/m3​​?

22. A satellite $X$ is in a circular orbit of radius $R$ with a period $T$ around Earth.

What will be the orbital radius of satellite Y, travelling in a circular orbit with a period of 8$T$ around Earth?

23. 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.

24. Two positive charges q1​ and q2​ are separated by a distance $d$. A third positive charge $q$ is placed at a distance d/4 from q1​ so that the charge $q$ is in equilibrium.

What is the ratio q1/q2​​?

25. The gravitational field strength on the surface of the moon is gE/6​​. Two objects of different masses $m$ and $2m$ are released with zero speed on the moon from heights of $h$ and $2h$, respectively, where $h$ is small compared to the radius of the moon.

What are the magnitudes of the accelerations of these objects right after release?