**1. Five resistors of equal resistance are connected to a cell as shown.**

What is correct about the power dissipated in the resistors?

**2. The electromotive force (emf) of a cell is defined as**

**3. A current is established in a coil of wire in the direction shown.**

The direction of the magnetic field at point P is

**4. A cell with negligible internal resistance is connected as shown. The ammeter and the voltmeter are both ideal.**

What changes occur in the ammeter reading and in the voltmeter reading when the resistance of the variable resistor is increased?

**5. Which diagram best represents the electric field due to a negatively charged conducting sphere?**

**6. The circuit shows a resistor R connected in series with a battery and a resistor of resistance 10 Ω. The emf of the battery is 20 V and it has negligible internal resistance. The current in the circuit is 1.0 A.**

Which of the following is the resistance of R?

**7. Three identical resistors are connected to a battery as shown.**

Which of the following is a correct statement?

**8. The diagram shows two current-carrying wires, P and Q, that both lie in the plane of the paper. The arrows show the conventional current direction in the wires.**

The electromagnetic force on Q is in the same plane as that of the wires. What is the direction of the electromagnetic force acting on Q?

**9. A positively-charged particle moves parallel to a wire that carries a current upwards.**

What is the direction of the magnetic force on the particle?

**10. An electron travelling at speed v perpendicular to a magnetic field of strength B experiences a force F.**

What is the force acting on an alpha particle travelling at 2*v* parallel to a magnetic field of strength 2*B*?

**11. An electron is accelerated through a potential difference of 2.5 MV. What is the change in kinetic energy of the electron?**

**12. Which of the following diagrams illustrates the electric field pattern of a negatively charged sphere?**

**13. In the circuits below the cells have the same emf and zero internal resistance. The resistors all have the same resistance.**

Which of the following gives the ratio power dissipated in X

**14. A positively charged particle enters the space between two charged conducting plates, with a constant velocity directed parallel to the plates, as shown.**

The top plate is positively charged and the bottom plate is negatively charged. There is a magnetic field in the shaded region PQRS. The particle continues to move in a horizontal straight line between the plates. Which of the following correctly describes the magnetic field direction?

**15. A beam of electrons moves between the poles of a magnet.**

What is the direction in which the electrons will be deflected?

**16. A cell has an emf of 4.0 V and an internal resistance of 2.0 Ω. The ideal voltmeter reads 3.2 V.**

What is the resistance of R?

**17. Three resistors are connected as shown. What is the value of the total resistance between X and Y?**

**18. Two resistors X and Y are made of uniform cylinders of the same material. X and Y are connected in series. X and Y are of equal length and the diameter of Y is twice the diameter of X.**

The resistance of Y is *R*.

What is the resistance of this series combination?

**19. A metal wire X with length L and radius r has a resistance R. A wire Y of length 4L made from the same material as X has the same resistance R. What is the radius of Y?**

**20. A cylindrical resistor of length**

`l` is made from a metal of mass m. It has a resistance R.

Two resistors, each of length 2`l` and mass `m/2,` are then created from the same volume of the metal.

What is the resistance of the two resistors when connected in parallel?

**21. Two rectangular blocks, X and Y, of the same material have different dimensions but the same overall resistance. Which of the following equations is correct?**

**22. A cell of emf ε and internal resistance r delivers current to a small electric motor.**

450 C of charge flows through the motor and 9000 J of energy are converted in the motor. 1800 J are dissipated in the cell. The emf of the cell is

**23. A resistor of resistance 12 Ω is connected in series with a cell of negligible internal resistance. The power dissipated in the resistor is P. The resistor is replaced with a resistor of resistance 3.0 Ω. What is the power dissipated in this resistor?**

**24. A proton is accelerated from rest through a potential difference of 1000 V. What is the potential difference through which an alpha particle must be accelerated to gain the same kinetic energy as the accelerated proton?**

**25. In the circuit shown, the fixed resistor has a value of 3 Ω and the variable resistor can be varied between 0 Ω and 9 Ω.**

The power supply has an emf of 12 V and negligible internal resistance. What is the difference between the maximum and minimum values of voltage *V* across the 3 Ω resistor?

**26. The diagram shows two equal and opposite charges that are fixed in place.**

At which points is the net electric field directed to the right?

**27. A wire carrying a current**

`I` is at right angles to a uniform magnetic field of strength B. A magnetic force F is exerted on the wire. Which force acts when the same wire is placed at right angles to a uniform magnetic field of strength 2B when the current is `I/4?`

**28. A –5µC charge and a +10µC charge are a fixed distance apart.**

Where can the electric field be zero?

**29. Three positive point charges of equal magnitude are held at the corners X, Y and Z of a right-angled triangle. The point P is at the midpoint of XY. Which of the arrows shows the direction of the electric field at point P?**

**30. An electron enters the vacuum between two oppositely charged plates with velocity**

`v`. The electron is followed by an alpha particle moving with the same initial velocity as the electron. A uniform magnetic field is directed out of the plane of the paper.

The electron’s path is undeflected. The path of the alpha particle will be

**31. A liquid that contains negative charge carriers is flowing through a square pipe with sides A, B, C and D. A magnetic field acts in the direction shown across the pipe.**

On which side of the pipe does negative charge accumulate?

**32. An electron enters the region between two charged parallel plates initially moving parallel to the plates.**

The electromagnetic force acting on the electron

**33. Two resistors, made of the same material, are connected in series to a battery. The length of resistor X is twice that of resistor Y, and X has twice the cross-sectional area of Y.**

Which of the following gives resistance of X

**34. A +3 C charge and a −4 C charge are a distance x apart. P is a distance x from the +3 C charge on the straight line joining the charges.**

What is the magnitude of the electric field strength at P?

**35. What is the definition of electric current?**

**36. The magnetic field produced by a current in a straight wire is in**

**37. Which of the following will not give rise to a magnetic field?**

**38. One electronvolt is equal to**

**39. An electron passes the north pole of a bar magnet as shown below.**

What is the direction of the magnetic force on the electron?

**40. Two electrodes, separated by a distance d, in a vacuum are maintained at a constant potential difference. An electron, accelerated from one electrode to the other, gains kinetic**

energy *E*_{k}.

The distance between the electrodes is now changed to `1/3d.`

What is the gain in kinetic energy of an electron that is accelerated from one electrode to the other?

**41. A battery of internal resistance 2 Ω is connected to an external resistance of 10 Ω. The current is 0.5 A.**

What is the emf of the battery?

**42. A battery of emf 6.0V is connected to a 2.0Ω resistor. The current in the circuit is 2.0A. The internal resistance of the battery is**

**43. Coulomb’s law refers to electric charges that are**

**44. An electric circuit consists of three identical resistors of resistance R connected to a cell of emf ε and negligible internal resistance.**

What is the magnitude of the current in the cell?

**45. Three resistors of resistance R are connected in parallel across a cell of electromotive force (emf) V that has a negligible internal resistance. What is the rate at which the cell supplies energy?**