The newest 20 of 76 written questions. Open one to see it on the real paper.
Explain whether the sign of the charge on the particles is positive or negative.
See it on the paper →Explain why the path followed by the beam of particles inside the magnetic field is circular.
See it on the paper →Use the information in 6(c)(i) to determine the flux density B of the uniform magnetic field. Give a unit with your answer.
See it on the paper →The particles in 6(b) are replaced with particles that have half of the charge and a quarter of the mass of the particles in 6(b). The sign of the charge and the speed of the particles are both unchanged. On Figure 6.1, draw the path of this beam of particles.
See it on the paper →Explain whether the sign of the charge on the particles is positive or negative.
See it on the paper →Explain why the path followed by the beam of particles inside the magnetic field is circular.
See it on the paper →Use the information in 6(c)(i) to determine the flux density B of the uniform magnetic field. Give a unit with your answer.
See it on the paper →The particles in 6(b) are replaced with particles that have half of the charge and a quarter of the mass of the particles in 6(b). The sign of the charge and the speed of the particles are both unchanged. On Figure 6.1, draw the path of this beam of particles.
See it on the paper →State an expression, in terms of some or all of m, Q, B and v, for the magnetic force F that acts on the particle when it is at point Y. F =
See it on the paper →On Fig. 7.1, draw an arrow at point Y to indicate the direction of the force in (b)(i).
See it on the paper →On Fig. 7.1, draw a line to show a possible path for the particle through the region of the magnetic field.
See it on the paper →Explain how an electric field can be used with the magnetic field to ensure that the particle in (b) now passes through point Z.
See it on the paper →Derive an expression for v in terms of B and the electric field strength E. v =
See it on the paper →State an expression, in terms of some or all of m, Q, B and v, for the magnetic force F that acts on the particle when it is at point Y. F =
See it on the paper →On Fig. 7.1, draw an arrow at point Y to indicate the direction of the force in (b)(i).
See it on the paper →On Fig. 7.1, draw a line to show a possible path for the particle through the region of the magnetic field.
See it on the paper →Explain how an electric field can be used with the magnetic field to ensure that the particle in (b) now passes through point Z.
See it on the paper →Derive an expression for v in terms of B and the electric field strength E. v =
See it on the paper →The potential difference (p.d.) between the plates of the velocity selector is V. The separation of the plates is d and the magnetic flux density is B. Show that the speed u of ions that pass undeviated through the velocity selector is given by V . Bd u =
See it on the paper →Determine B. B = T (b) Positive ions with kinetic energy 4.1 × 10 –17 J and mass 3.2 × 10 –27 kg pass undeviated through the velocity selector when V is equal to 980 V and d is equal to 3.6 × 10 –2 m.
See it on the paper →Many candidates reproduced the algebra involved in this syllabus derivation correctly. However, only a minority established the core physics behind the derivation as a starting point, the equality between the magnitudes of the electric and magnetic forces.
— Examiner report, February/March 2025, 9702/42 Q6(a) (Cambridge)
This question was generally well-answered, with many candidates successfully calculating the correct answer.
— Examiner report, February/March 2025, 9702/42 Q6(b) (Cambridge)
Many candidates explained why the particles pass through the field region undeviated, rather than addressing the question asked, which focussed on the expression in part (a) and how this expression shows that the speed for undeviated path is independent of the mass and charge of the particle. Many other candidates, who did address the question asked, gave only one of the factors of mass and charge...
— Examiner report, February/March 2025, 9702/42 Q6(c) (Cambridge)
Past papers, syllabus and examiner reports © UCLES (Cambridge University Press & Assessment). Questions are matched to topics from the official syllabus. AssessPro is independent and not endorsed by Cambridge.