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## SA1 Previous Question Papers in Science for class 9 and 10 (CBSE) with marking Scheme

As per request from numerous student visitors, we are publishing some previous question papers used in the previous years. You can use them to prepare for the present exams and score better marks. The previous question papers give a hint on the type of questions. Practice the questions below to check your timing.

Class X Science SA1 Previous Question Paper 2

Class X Science Answer Key 2

Class IX Science SA1 Previous Question Paper 1

Class IX Science SA1 Answer Key 1

Class IX Science SA1 Previous Question Paper 2

Class IX Science SA1 Answer Key 2

## Discuss the Difficult questions of AISSCE 2012

How was the Physics Question Paper for AISSCE (CBSE Class 12) 2012?

Many students complained that many questions of Physics question paper AISSCE 2012 were unexpected and hard.

Do you think so?

Post the questions you felt hard or unexpected here as comment to this post. Let us discuss them here.

## A fill up exercise for class 9 Physics from the chapter “Sound”

Dear students,

Find below some of the fill in the blanks questions  from the chapter sound. (Class 9 Science) Practisinf fill in the blanks typwe questions helps better comprehension and thorough reading of the text book. As a follow up you can try making more fill in the blanks type questions yourself from the textbook.

1. ______ is a form of energy which produces a sensation of hearing to our ears.
2. λ is a symbol of representing _____________.
3. __________ is the reciprocal of frequency.
4. Mechanical waves are of two types; _____________ and ______________.
5. Sound waves travel in the form of ____________ and __________________.
6. Transverse waves propagate in the form of _________ and _____________.
7. The maximum displacement of the wave from mean position is called ______________.
8. Number of vibrations completed in one second is called ________________.
9. The distance between two consecutive compressions or two consecutive rarefactions is called ______________.
10. Sound of frequency below 20 Hz is called _____________
11. velocity of sound = ___________ x wavelenth
12. Sound cannot travel in _____________
13. Sound of frequency greater than 20 kHz is called ___________
14. _______________ is used to check abnormalities of fetus.
15. SI unit of frequency is _________.
16. ____________ is a device used to measure the depth of sea.
17. SONAR’s full form is __________________________________
18. Sound travels fastest in ____ medium
19. Loudness of sound depend on _____ of vibration.
20. Audible range for human beings is from _ Hz to ___ Hz.
21. Bats detect their prey using ___________– waves.
22. Sound heard after reflection from an obstacle or boundary is called ________-.
23. The persistence of sound after the source has stopped vibrations is called ________.
24. ___________ is a device used by doctors and its working is based on multiple reflection of sound.
25. Loudness of sound is determined by the ___________ of vibrations.
26. Checking the functioning of heart with the help of ultrasound is called ________________
27. The outer ear is also called ________
28. Another function of human ear is to _____________ our body.
29. _______ of ear collects sound from the surroundings.
30. Ultrasound are produced by some animals like __________, _____________ and _____________.
31. Electrical signals from ear are send to the brain via _____________
32. The three bones of the ear which amplifies the vibrations are _______ , ______________ and ____________.
33. ______________ converts sound into electrical signals.
34. The smallest bone in ear is __________ which is also the smallest bone in human body.
35. ____________ are regions of higher density and pressure when sound propagates through a medium.

## Mystery Spot and Physics

Mystery spot is a tourist attraction located near Santa Cruz , California. It is a place where the laws of physics and gravity do not apply.
The Mystery Spot is a gravity hill, a tilt indused visual illusion. In the tilted room of the mystery spot , misperceptions of the height and orientation of objects occur. Explain.

## DECREASING PRESSURE BY INCREASING AREA

The pressure exerted by a given force can be decreased by increasing the area of contact.

# P=F/A

The equation shows that pressure is inversely proportional to area.

## FOUNDATION OF BUILDINGS

The foundation off building is made more broader than the rest of the building so that the pressure exerted by the weight on earth can be decreased.

## SHOULDER STRAPS OF SCHOOL BAGS

The shoulder straps of school bags are made wider and soft so that the pressure exerted by the heavy bags on shoulders can be reduced. You can feel the paining pressure if you try to replace the broad strap with a narrow one.

FEET OF ELEPHANT AND CAMEL

## MILITARY TANK

The Military tanks have a broad chain so that the pressure exerted by the heavy vehicle on ground is a minimum and it can travel even through marshy places

• Heavy Vehicles have more tyres
• When vehicles get struck in marshy places, wooden planks are used for the vehicle to come up.

## Collection of Problems received from Class 12 Physics

These problems were posted by Geena. Hope that we will be able to post the answers to these questions soon; each in a separate post. By the time visitors can attempt to post their answers as comments to this post. (Only selected posts will be published)

Please note that the answers are not published until the Physics teachers are not satisfied with the answers. So, please be patient to get the correct answers rather than approximations in a haste.

If you want real time answers to your queries by a group of Physics Lovers, you can post them at the Physics Fans group with facebook at https://www.facebook.com/groups/askphysics/

1. A series battery of 10 lead accumulators each of emf 2 V and internal resistance 0.25 ohm is charged by a 220 V D.C. mains to limit the charging current a resistance of 47.5 ohm is used in series in the charging circuit. What is a) the power supplied by the mains and b) power dissipated as heat? Account for the difference of powers is (a) and (b).
2. A potentiometer wire has a length L and a resistance Ro. It is connected to a battery and
a resistance combination as shown. Obtain an expression for the potential drop per unit length of this potentiometer wire. What is the maximum emf of a ‘test cell’ for which one can get a ‘balance point’ on this potentiometer wire? What precaution should one take, while connecting this ‘test cell’ , in the circuit?
3. A cell, of emf 4 V and .internal resistance 0.5 Ω, is connected across a load of resistance (i) 7.5 Ω, (ii) 11.5 Ω. Calculate (i) the ratio of the differences in the emf of the cell and the potential drop across the load, and (ii) the ratio of the currents in the two cases.
4. In the figure shown, calculate the total flux of the electrostatic field through the spheres S1 and S2 The wire, AB, shown here, has a linear charge density, λ given by λ = kx where x is the distance measured along the wire, from the end A.
5. A straight wire, of length L, carrying a current I, stays suspended horizontally in mid air in a region where there is a uniform magnetic field B . The linear mass density of the wire is λ. Obtain the magnitude and direction of this magnetic field.
6. Two cells of same emf E, but different internal resistance rl and r2 are connected to an external resistance R as shown. in the figure. The voltmeter V reads zero. Obtain an expression for R in terms of rl and r2. Calculate the voltage across the cell of internal resistance r2. (Assume that the voltmeter V is of infinite resistance).
7. A galvanometer with a coil of resistance 120 ohm shows full scale deflection for a current of 2.5 mA How will you convert the galvanometer into an ammeter of range 0 to 7.5 A ? Determine the net resistance of the ammeter. When an ammeter is put in a circuit, does it read slightly less or more than the actual current in the original circuit? Justify your answer.
8. Figure shows a bar magnet M falling under gravity through an air cored coil C. Plot a graph
showing the variation of induced e.m.f (E) with time (t). What does the area enclosed by the
E – t curve depict ?
9. The electron in the hydrogen atom circles around the proton with a speed of 2.18 x 106 m/s in an orbit of radius 5.13 x 10 -11 m. What magnetic field does it produce at the centre?
10. A proton moves with a speed of 7.45 x 105 m/s directly towards a free proton originally at rest. Find the distance of the closest approach for the two protons. (Given: mass of proton = 1.67 x 10–27 kg and e = 1.6 x 10 –19 C)
11. Figure (a), (b) and (c) show three a.c. circuits in which equal currents are flowing. If the frequency of emf be increased, how will the current be affected in these circuits? Give reason for your answer.

## How to tackle problems with constraint relations?

“Can you suggest a way to tackle problems on constraint relations easily??” – Aritra posted this question.

Answer: The common way to solve problems involving constraints is to replace the constraints with their reaction forces. As the question is not specific, I cannot tell much now. If you have further doubts regarding this issue, please post as comments to this post.

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