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Physics - Paper II
For Class XII (Science Group)
Model papers 2020 -2021
The correct answer of number mcqs no. (xix) is waxed paper
SECTION "B" (SHORT ANSWER QUESTION) (28 Marks)
Q.2(i):
Data:
Rg = 50 Ω
Ig = 5 mA = 5 x 10-3 A
Rx = 0.1 MΩ = 0.1 x 106 Ω
v =?
Formula:
Rx = -V / Ig - Rg
Rx + Rg = -V / Ig
Or
V = Ig(Rx + Rg)
Solution:
V = 5 x 10-3 (0.1 x 106 + 50)
V = 5 x 10-3 (100000 + 50)
V = 5 x 10-3 (100050)
V = 500250 x 10-3
V = 500.25 V Ans
Q.2(ii):
Data:
di = 5 cm
ΔL = 0.01 mm = 0.01 / 10 = 0.001 cm
ΔT = 30 °C
αi= 1.2 x 10-5 C-1
αb= 1.9 x 10-5 C-1
Formula:
ΔL = αLo ΔT
Solution:
ΔLi = αi di ΔT
ΔLb = αb db ΔT
ΔL = ΔLi - ΔLb
di ≅ db
0.001 = αi di ΔT - αb di ΔT
0.001 = di (αi - αb) ΔT
0.001 = 5 (1.2 x 10-5 - 1.9 x 10-5) ΔT
ΔT = 0.001 / 5 x 0.7 x 10-5
ΔT = 28.5 °C
Final temperature
T = 28.5 + 30
T + 58.5 °C Ans
Q.2(iv):
Data:
RH = 1.0967800 x 107 m = 1.097 x 107 m
nf = 2 (Balmer)
a) ni = 3 (Largest)
b) ni = ∞ (Shortest)
λmax = ?
λmin = ?
Formula:
1/ λmax = RH ( 1/nf2 - 1/ni2)
1/ λmin = RH ( 1/nf2 - 1/∞)
Solution:
For Longest Wavelength
Q.2(v):
Data:
m = 2mo
a) V =?
b) P = ?
Q.2(vi):
Data:
Number Of Bulbs = b = 5
Power Of Bulb = Pb = 100 W
Number Of Fans = f = 10
Power Of Fan = Pf = 60 W
Number Of Lights = l = 10
Power Of Light = Pl = 40 W
Number Of Iron = i = 1
Power Of Iron = Pi = 1000 W
Time = t = 4 x 30 x 60 x 60 = 432000 sec
Energy = E = ? (Kwh)
R = 90 paisa / unit
Cost = ?
Formula:
E = P x t
P = E / F
Solution:
Total Power:
Bulb = P1 = b x Pb = 5 x 100 = 500 W
Fan = P2 = f x Pf = 10 x 60 = 600 W
Light = P3 = l x Pl = 10 x 40 = 400 W
Iron = P4 = i x Pi = 1 x 1000 = 1000 W
P = P1 + P2 + P3 + P4
P = 500 + 600 + 400 + 1000 = 2500 W
E = P x t
E = 2500 x 432000
E = 1.08 x 109 J
1 kwh = 3600 000 J
E = 1.08 x 109 / 36 x 105
E = 300 kwh Ans.
b) Cost
Cost = Kwh x Rate
Cost = 300 x 0.9
Cost = 270 Rs. Ans.
SOURCE: Board Of Intermediate Education Karachi
Mcqs number (xix) is wrong
ReplyDeleteYes, you are right, correct answer is waxed paper.
DeleteJAZAKALLAH
Yes its waxed paper
DeleteThank you for your feedback
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