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Roll No. Name Class & Section

SUCATION SOCT

APEEJAY COMMONANNUAL EXAMINATION, 2019-20 PHYSICS (042)

Time Allowed: 3.00 Hrs.

Class - XI

Maximum Marks: 70

General Instructions:

1. All Questions are compulsory. There are 37 questions in all.
2. This question paper has four sections: Section A, Section B, Section C and Section D
3. Section A contains 20 questions of one mark each, Section B contains 7 questions of two marks each, Section C contains 7 questions of three marks each and Section D contains 3 questions of five marks each.

1. There is no overall choice. However, internal choices have been provided in 2 questions of one mark, 2 questions of two marks, 2 questions of three marks and 3 questions of five marks. You have to attempt only one of the choices in such questions.

1. You may use the following values of physical constants wherever necessary.

<math>c=3 \times 10^8 \, m/s</math>

<math>h=6.63\times 10^{-34} J_S</math>

<math>e=1.6 \times 10^{-19} C</math>

<math>m_e = 9.1 \times 10^{-31} \, kg</math>

<math>m_n = 1.675 \times 10^{-27} \, \text{kg}</math>

<math>m_p = 1.673 \times 10^{-27} \, kg</math>

Avogadro's number = 6.023 × 10²³ per gram mole

Boltzzmann constant= 1.38 × 10-23 JK

Section-A

Directions (Q.Nos 1 - 10)

Select the most appropriate option from those given below each question. R/8 [.P.T.O.]

1. Doppler's effect holds good for
2. Only sound waves.
3. Only electromagnetic waves.
4. Both (a) and (b).
5. None of these.

1. Two wave trains <math>Y_1 = \alpha \sin{(4000\pi t)}</math> and <math>Y_2 = \alpha \sin{(4008\pi t)}</math> are approaching each other . The number of beats heard per second is
2. 8 (b) 4
3. (d) 0

1. The average velocities of the objects A and B are VA and VB respectively. The velocities are related such that VA>VB. The position-time graph for this situation can be represented as

,(a) (b) 20

x(m) 80 - x(m) 60 - 40

1. 10 - 0

0 2 1=3 4 5 1(5)-

1(5) - ·B (c) (d) None of these

T 120 + 100 + <math>x(m) 80 +</math> 60 - 40 - 20 - 10 - 0- 0 2 3 t(s) - OR R-8/Physics (042)/XI [2]