A-LevelPhysicsElectric fields9702/22 · Feb/Mar 2020 · Q67 Marks
A uniform electric field is produced between two parallel metal plates. The electric field strength is 1.4 × 10⁴ NC⁻¹. The potential difference between the plates is 350 V.
- (a)Calculate the separation of the plates.[2]
- (b)(i)A nucleus of mass 8.3 × 10⁻²⁷ kg is now placed in the electric field. The electric force acting on the nucleus is 6.7 × 10⁻¹⁵ N. Calculate the charge on the nucleus in terms of e, where e is the elementary charge.[3]
- (b)(ii)Calculate the mass, in u, of the nucleus.[1]
- (b)(iii)Use your answers in (b)(i) and (b)(ii) to determine the number of neutrons in the nucleus.[1]
Mark scheme
Marking points from the official mark scheme (Feb/Mar 2020). The mark or mark type is shown in brackets.
- C1 E= V/d
- C1 d = 350/1.4 × 10⁴
- A1 = 0.025 m
- C1 E = F/Q
- C1 = 6.7 × 10⁻¹⁵ / 1.4 × 10⁴ (= 4.8 × 10⁻¹⁹ C)
- A1 = (4.8 × 10⁻¹⁹ / 1.6 × 10⁻¹⁹) е
- A1 = 3.0 e
- A1 mass = 8.3 x 10⁻²⁷ / 1.66 × 10⁻²⁷
- A1 = 5.0 u
- A1 number = 5 – 3
- A1 = 2
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