An α-particle moves in a straight line through a vacuum with a constant speed of 4.1 × 10⁶ms⁻¹. The α-particle enters a uniform electric field at point A, as shown in Fig. 4.1. [Figure 4.1] The α-particle continues to move in the same straight line until it is brought to rest at point B by the electric field. The deceleration of the α-particle by the electric field is 2.7 × 10¹⁴ ms⁻².

1. (a)State the direction of the electric field.[1]
2. (b)Calculate the distance AB.[2]
3. (c)Calculate the electric field strength.[3]
4. (d)The α-particle is at point A at time t = 0. On Fig. 4.2, sketch the variation with time t of the momentum of the α-particle as it travels from point A to point B. Numerical values are not required. [Figure 4.2][1]
5. (e)State the name of the quantity that is represented by the gradient of the graph in (d).[1]
6. (f)A β⁻ particle now enters the electric field along the same initial path as the α-particle and with the same initial speed of 4.1 × 10⁶ms⁻¹.
7. (f)(i)Calculate the kinetic energy, in J, of the β⁻ particle at point A.[3]
8. (f)(ii)State and explain the differences between the electric force on the β⁻ particle in the electric field and the electric force on the α-particle in the electric field.[3]
9. (f)(iii)The β⁻ particle is produced by the decay of a nucleus. State the name of another lepton that is produced at the same time as the β⁻ particle.[1]

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