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- Question
The working of the quartz crystal in the watch is based on the
Options- A. Piezo - electric Effect
- B. Edison Effect
- C. Photoelectric Effect
- D. Johnson Effect
- Correct Answer
- Piezo - electric Effect
- 1. Total internal reflection can take place when light travels from
Options- A. Air to glass
- B. Air to water
- C. Water to glass
- D. Diamond to glass Discuss
- 2. A boat loaded with rocks floats in the middle of a swimming pool. A man in the boat throws the rocks overboard. The level of water in the pool will
Options- A. increase
- B. decrease
- C. remains the same
- D. first decrease and then increase Discuss
- 3. Pick out the only scalar quantity
Options- A. power
- B. Electric field
- C. magnetic momentum
- D. average velocity Discuss
- 4. A ball is thrown vertically upwards. Assuming the air resistance to be constant and cosiderable:
Options- A. the time of ascent < the time of descent
- B. the time of ascent > the time of descent
- C. the time of ascent = the time of descent
- D. none of these Discuss
- 5. The base of an electric iron is brightly polished mainly
Options- A. to make it smooth and frictionless
- B. to make it rust-proof
- C. to reduce heat loss by radiation
- D. to make it more durable Discuss
- 6. If a carrier wave of 1000 kHz is used to carry the signal, the length of transmitting antenna will be equal to _____ ?
Options- A. 300 m
- B. 30 m
- C. 3 m
- D. 0.3 m Discuss
- 7. What is the full form of "RADAR" ?
Options- A. Radio Detecting and Ranging
- B. Region Device and Ranging
- C. Radio Detect and Rangs
- D. Radio Device and Ranging Discuss
- 8. The information of brilliant colors in a thin soap film is a consequence of the phenomena of
Options- A. Polarization and interference
- B. Diffraction and dispersion
- C. Multiple refraction and dispersion
- D. Multiple reflection and interference Discuss
- 9. Which of the following physical quantities do not have same dimensions
Options- A. Force and Pressure
- B. Work and Energy
- C. Impulse and momentum
- D. Weight and Force Discuss
- 10. Ball bearings are used in cycles, scooters etc to
Options- A. Increase the friction between the wheel and the axle
- B. Reduce the friction between the wheel and the axle
- C. Reduce the friction between ground and the whee
- D. None of the above Discuss
Physics problems
Search Results
Correct Answer: Diamond to glass
Correct Answer: decrease
Explanation:
Let M and m grams be the mass of boat + rock in it. By law of floatation(M+m) grams of water will be displaced. This has a volume of (M+m)cc. That means the level of water in pool has risen up by (M+m)cc with the boat + rock when it is floating. If the rocks in the boat are thrown not into the pool but outside, the weight left is only M grams the weight of the boat. This will have displaced M cc of water only i.e less water than in the case of loaded boat. But if the rocks are put in the water in the pool and not outside, then the water in the pool will rise not only by M cc on account of empty boat but also by a volume of the stone put into it. This volume will be where m is the mass of rock and d density of rock.
Now is < m. Thus the total rise will be which is < M + m.
Correct Answer: power
Correct Answer: the time of ascent < the time of descent
Correct Answer: to reduce heat loss by radiation
Explanation:
Polished surfaces are poor radiators of heat. So loss of heat on that account is reduced and the electric iron remains hotter than otherwise.
Correct Answer: 300 m
Correct Answer: Radio Detecting and Ranging
Correct Answer: Multiple reflection and interference
Correct Answer: Force and Pressure
Correct Answer: Reduce the friction between the wheel and the axle
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