A-LevelPhysicsElectric fields9702/22 · May/June 2019 · Q68 Marks
6 (c) A particle P has a mass of 0.15 u and a charge of –1e, where e is the elementary charge.
- (a)State what is meant by a field line (line of force) in an electric field.[1]
- (b)An electric field has two different regions X and Y. The field strength in X is less than that in Y. Describe a difference between the pattern of field lines (lines of force) in X and in Y.[1]
- (c)(i)Particle P and an α-particle are in the same uniform electric field. Calculate the ratio magnitude of acceleration of particle P / magnitude of acceleration of α-particle[3]
- (c)(ii)Particle P is a hadron composed of only two quarks. One of them is a down (d) quark. By considering charge, determine a possible type (flavour) of the other quark. Explain your working.[3]
Mark scheme
Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.
- [B1] path/direction in which a (free) positive charge will move
- [B1] (lines) closer together in Y/further apart in X
- [C1] a = Eq/m (or F = Eq and F = ma)
- [C1] ratio = (1e/0.15 u) × (4 u / 2e) or 1/0.15 × 4/2
- [A1] ratio = 13
- [C1] down quark charge is –(1/3)e
- [A1] - (1/3)e + q = −1e so q = −(2/3)e
- [B1] (–(2/3)e is) anti-up / ū (quark) (allow charm or top antiquark)
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