# Grade Eleven Physics Board Exam Questions

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### Grade Eleven Physics Board Exam Questions

Class: XI                                                                                                                     F.M.:75

Subject: Physics                                                 Time: 3 hrs                              P.M.: 30

General instructions:

G = 6.67X10-11 Nm2kg-2, g = 10ms-2, Radius of the earth (R) = 6.4 x 106m, Y = 2 x 10-11Nm-2, surface tension of water (T) = 7×10-2 Nm-1. Latent heat of fusion of ice (L) = 80 calgm-1. Group ‘A’

### Answer any six questions in brief. (2×6=12)

1. Hearing rattles of snake a person makes two displacements of 1.8m and 2.4m. If the resultant displacement is 3m, how is it possible? Explain.
2. Why do we slip on muddy roads?
3. The earth is closer to the sun in December than in June. In which month does it move faster in its orbit?
4. An astronaut in satellite feels weightlessness. Why?
5. If the ice in polar caps melts, how does it affect the length of a day?
6. Water is more elastic than air. Why?
7. A boat sinks more in river water or sea water. Explain.
8. Explain in terms of breaking stress, why elephant has thicker legs as compared to human beings?

### Answer any two questions in brief: (2×2=4)

1. Why is an ice cube at 00c more effective in cooling a drink than water at 00c?
2. Why does a diesel engine need to spark plug?
3. A cylinder filled with gas is being carried inside the fast moving train, what change will be there in the internal energy of the gas?
4. Answer, in brief any one question: (2×1=2)
5. Why is there summer in June & winter in December in the northern hemisphere of the earth?
6. Can mirrors give rise to chromatic aberration? Explain.
7. Attempt any one question in brief: (2×1=2)
8. A man inside an insulated metallic cage does not receive a shock when it is highly charged. Explain.
9. It is possible to charge a capacitor to any potential?

Group ‘B’

### Answer any three questions  ( 4×3=12)

1. Deduce an expression for rise of a liquid in a capillary tube. What happens if the length of the capillary tube is less than that required for the rise of a liquid in it?
2. Obtain an expression for the total energy in a S.H.M. and represent it graphically.
3. What is
4. moment of inertia? Find an expression for K.E. of a rolling body in the horizontal plane.
5. State and prove Bernoulli’s theorem.

### Answer any two questions  ( 4×2=8)

1. State Boyle’s law and Charle’s law. Show how they can combine to give the equation of state of an ideal gas.
2. Prove that CP – CV = R, where the symbols carry their usual meanings.
3. What is a black body? State and explain the Stefan’s law of black body radiation.

### Answer any one question  (4×1=4)

1. Derive the lens maker’s formula, where the symbols carry their usual meanings.
2. Explain the working of an astronomical telescope and hence calculate the angular magnification when image forms at least distance of distinct vision.

### Answer any one question: (4×1=4)

1. State and explain Gauss’s law. Use it to formulate the electric field intensity at a point due to an infinitely long line charge.
2. What is polarization vector? Deduce an expression connecting three vectors, and, where the symbols carry their usual meanings.

Group ‘C’

### Solve any three numerical problems.(4×3=12)

1. A man can jump 1.5m on earth. Calculate the approximate height he might be able to jump on a planet whose density is one quarter that of earth and where radius is one third of the earth.
2. The speed of a body spinning about an axis increases from rest to100 rev/min in 5 seconds, if a constant torque of 20Nm is applied. The external torque is removed and the body comes to rest in 100sec due to friction. Calculate the frictional torque.
3. A wire of length 3m and cross section 10-6 m2 has a mass of 15kg hung on it. What is the extension produced? How much energy is stored in stretched wire?
4. A body is projected down at an angle 300 with the horizontal from the top of a building 170m high. Its initial speed is 40 m/s. How long will it take to strike the ground? How far from the foot of the building the body will strike and at what angle with the horizontal?

#### Grade Eleven Physics Board Exam Questions

Solve any two numerical problems. (4×2=8)

1. Calculate the rate at which heat will conduct from the interior of human body. Assume that the thickness of tissue is 4cm, the skin is at 340c, the interior is at 370c and the surface area is 1.5m2. (K = 0.2 wm-1k-1)
2. A petrol engine consumes 5kg of petrol per hour. If the power of the engine is 20kw and the calorific value of petrol is 11 x 103 kcal/kg, calculate the efficiency of engine.
3. A copper vessel of volume exactly 1.8m3 at a temperature of 200c is filled with glycerine. If the temperature rises to 300c, how much glycerine will spill out? Given ¡ for glycerine is 5.3 x 10-4K-1 and that of copper is 16.7 x 10-6K-1.
4. A narrow beam of light is incident normally on one face of an equilateral prism (refractive index 1.45), the prism being surrounded by water (refractive index 1.33). At what angle the ray of light emerges out?