Advanced level 2025 North West mock Physics guide

Advanced level 2025 North West mock Physics guide

Advanced level 2025 North West mock Physics guide

2. a) From graph,
Q0 = 56 µC, 1
2
Q0 = 28 µC, (1) Δt = 𝑡1
⁄2= 9s (1)
b) Q = 𝑄0𝑒
-𝑡
𝐶𝑅 ⇒
𝑑𝑄
𝑑𝑡
=
-1
𝐶𝑅
𝑄0𝑒
-𝑡
𝐶𝑅
I = – 𝑑𝑄
𝑑𝑡
⇒ I = 1
𝐶𝑅
𝑄0𝑒
-𝑡
𝐶𝑅 ⇒ I0 = 𝑄0
𝐶𝑅
I0 = 56 𝑥 10-6
9 𝑠
𝐶 (1) ⇒ I0 = 6.2 x 10-6 A (1)
c) C = 18.8 nF, Q0 = CE ⇒ E = 𝑄0
𝐶
E = 56 𝑥 10-6 𝐶
18.8 𝑥 10-6𝐹 (1) ⇒ E = 3.0 V (1)
(6 marks)
3. a) the sources
– must be coherent ie same frequency and
should either be in phase or have a constant
phase difference (1)
– very close to each other (1)
b) λ = 480 x 10-9 m, fringe separation y = 25.6 𝑚𝑚
20
y = 1.28 x 10-3 m, d = 0.4 x 10-3 m but y = 𝜆𝑥
𝑑
⇒
𝑥 =
𝑑𝑦
𝜆 ⇒ 𝑥 =
0.4 𝑥 10-3 𝑥 1.28 𝑥 10-3
480 𝑥 10-9 m (1)
𝑥 = 1.1 𝑚 (1)
𝑐) the fringe separation decreases (1)
λblue < λgreen , from y = 𝜆𝑥
𝑑
, y α λ (1)
(6 marks)
4. a) law of conservation of energy (1)
b) -3 correct equations from Kirchoff’s laws
(1) x 3
– solving the equations simultaneously (1)
– current through 18 Ω resistor = 0.7 A, current
through 5 Ω resistor = 1.4 A, current through
4 Ω resistor = 2.1 A (1)
(6 marks)
5. a)
The string breaks when the oject is vertically below the
centre of the circle as then the tension in the string is
maximum (1)
T – mg = 𝑚𝑣2
𝑟
⇒ 𝑇
𝑚𝑎𝑥 – mg =
𝑚𝑣𝑚𝑎𝑥 2
𝑟
𝑇
𝑚𝑎𝑥 = 62 N, m = 200 g = 0.2 kg, r = 80 cm = 0.8 m
Substitution (1), 𝑣𝑚𝑎𝑥 = 15.5 ms-1 (1)
b) When the string breaks, the particle becomes a
projectile projected horizontally at a speed of 15.5 ms-1
sy = uyt +
1 2
ayt2; sy = -3 m, uy = 0, ay = – 9.8 ms-2
⇒ time to strike the ground t = 0.8 s (1)
𝑣 = 𝑢 + 𝑎𝑡 ⇒ 𝑣𝑥 = 𝑢𝑥 + 𝑎𝑥𝑡, 𝑎𝑥 =0, ⇒ 𝑣𝑥= 15.5 ms-1
𝑣𝑦
= 𝑢
𝑦 + 𝑎𝑦𝑡 ; 𝑢𝑦= 0, 𝑎𝑦 = -𝑔, 𝑡 = 0.8 𝑠
𝑣𝑦
= (-9.8)(0.8) ⇒ 𝑣𝑦 = -7.8 𝑚𝑠-1
v ⃑ = [(15.5)𝐢 – (7.8)𝐣]ms-1 (1)