Define the coulomb.

1. (a)Define the coulomb.[1]
2. (b)(i)Two vertical metal plates in a vacuum have a separation of 4.0cm. A potential difference of 2.0 × 10² V is applied between the plates. Fig. 5.1 shows a side view of this arrangement. [Figure 5.1] A smoke particle is in the uniform electric field between the plates. The particle has weight 3.9 × 10⁻¹⁵N and charge -8.0 × 10⁻¹⁹C. Show that the electric force acting on the particle is 4.0 × 10⁻¹⁵ N.[2]
3. (b)(ii)On Fig. 5.1, draw labelled arrows to show the directions of the two forces acting on the smoke particle.[1]
4. (b)(iii)The resultant force acting on the particle is F. Determine 1. the magnitude of F, 2. the angle of F to the horizontal.[3]
5. (c)The electric field in (b) is switched on at time t = 0 when the particle is at a horizontal displacement s = 2.0 cm from the left-hand plate. At time t = 0 the horizontal velocity of the particle is zero. The particle is then moved by the electric field until it hits a plate at time t = T. On Fig. 5.2, sketch the variation with time t of the horizontal displacement s of the particle from the left-hand plate. [Figure 5.2][2]

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