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- Question
Radio waves sent out by a radio stations are reflected by
Options- A. troposphere
- B. stratosphere
- C. mesosphere
- D. ionosphere
- Correct Answer
- ionosphere
ExplanationThis is a layer of atmosphere about 60 to 70 km above the earth and extends to about 400km. It contains ionised particles which can reflect radio waves making radio communication round the world possible.
- 1. Tap water is placed in an open pad and allowed to evaporate. After some time the temperature of water
Options- A. increases to a great extent
- B. increases slightly
- C. decreases slightly
- D. decreases rapidly Discuss
- 2. The cover of a solar coker is made of glass because
Options- A. it absorbs sun's rays
- B. it reflects sun's rays
- C. it retains the heat inside by the green house effect
- D. it rediates heat better than metals Discuss
- 3. The fact that two large ships travelling on close parallel courses in the same direction tend to move towards each other can be explained by
Options- A. Bernoulli's principle
- B. Magnetic properties of the ship's material
- C. Newton's third law of motion
- D. Earth's gravitational force Discuss
- 4. A capillary tube is partially dipped vertically in a vessel containing water. Due to capillarity water rises in the tube. The height of water rise in the tube can be increased by
Options- A. decreasing the radius of the capillary tube
- B. increasing the radius of the capillary tube
- C. increasing the height of water in the vessel
- D. None of these Discuss
- 5. Solids have definite shapes.This is because
Options- A. the forces of cohesion of the molecules within are very much less in them
- B. the forces of cohesion are very large
- C. the forces of adhesion are large
- D. the forces of adhesion are less Discuss
- 6. A series of fast moving still pictures can be made to appear as a moving picture because the eye
Options- A. can focus very rapidly as pictures change
- B. is quicker than the brain
- C. can see 2 images separated only if the interval betwen seeing them is more than one-tenth of a second
- D. can shut out some of the light Discuss
- 7. An integrated circuit is more advantages than a coventional circuit because
Options- A. they make the electric equipments more reliable and easier for servicing
- B. a faulty part of a conventional circuit may be difficult to locate and repair
- C. if a part of the integrated circuit fails the entire circuit is simply replaced
- D. all the above Discuss
- 8. A bimetal made copper and iron strips welded together is straight at room temperature. It is held vertically with iron strip towards left and copper strip towards right. If this bimetal is heated , it will
Options- A. remain straight
- B. bend towards right
- C. bend towards left
- D. none of these Discuss
- 9. The ability to do work is called Energy.
Options- A. TRUE
- B. FALSE Discuss
- 10. Which part of the flame is the hottest?
Options- A. Blue Zone
- B. Luminous Zone
- C. Dark Zone
- D. Non - Luminous Zone Discuss
Physics problems
Search Results
Correct Answer: decreases slightly
Explanation:
Evaporation causing cooling.Here the evaporation is less. Therefore cooling is less.
Correct Answer: it retains the heat inside by the green house effect
Explanation:
As the inside of the cooker is painted black, heat absorption is more producing heat waves of longer wavelength which cannot escape through glass and hence are trapped inside. Thus the food is cooked.
Correct Answer: Bernoulli's principle
Explanation:
The rapid flow of air between the two moving ships causes a reducton of pressure (Bernoulli's principle) , so they (the ships) are drawn closer together
Correct Answer: decreasing the radius of the capillary tube
Explanation:
The water rise in a capillary tube dipped in water is such that the weight of water in the tube above the surface of water in the vessel is equal to the upward force due to surface tension. So it is clear that if the bore to the tube is decreased , the height of the water column in it must be greater.
Correct Answer: the forces of cohesion are very large
Explanation:
Cohesion refers to attraction between molecules of the same kind while adhesion refers to attraction between different kinds of molecules
Correct Answer: can see 2 images separated only if the interval betwen seeing them is more than one-tenth of a second
Explanation:
The eye can see images separately only if they are exhibited at an interval of more than 1/10 of a second. In the case of a movie, the still pictures come one after the other at less than this minimum interval. So we do not see them separately but only as a continuous moving picture.
Correct Answer: all the above
Explanation:
Integrated circuit (IC) is a tiny device that controls electric signals in such electronic equipments as computers and T.V sets. Many integrated circuits contain thousands of electronic parts on a paper - thin chip of silicon. These parts include capacitors, diodes, all in a very small, compact space.
Correct Answer: bend towards left
Correct Answer: TRUE
Explanation:
Yes, the ability to do work is called Energy is True.
Correct Answer: Blue Zone
Explanation:
Blue Zone is the hottest part of the flame that is where the flame has the most Oxygen and you are getting complete combustion. It is about 1400 degrees Centigrades. The Reddish part (Non - Luminous Zone) is the coolest part, about 800 deg C.
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