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- Question
A wire of copper having length I and area of cross-section A is taken and a current / is flown through it. The power dissipated in the wire is P. If we take an aluminium wire having same dimensions and pass the same current through it, the power dissipated will be
Options- A. P
- B. < P
- C. > P
- D. 2P
- Correct Answer
- > P
ExplanationAluminum has a resistivity varying from 2.65 to 2.82 × 10?8 ? m.The resistivity of copper is generally given as: 1.72 x 10-8 ?.m.So, since resistivity of aluminium is higher than that of copper, so Power dissipated will be greater than P. this is because rest of the factors (l, A and i) are constant.
- 1. When the Sun is near the horizon during the morning or evening, it appears reddish. The phenomenon that is responsible forth is observation is
Options- A. reflection of light
- B. refraction of light
- C. dispersion of light
- D. scattering of light Discuss
- 2. Two metallic wires made from copper have same length but the radius of wire 1 is half of that of wire 2. The resistance of wire 1 is R. If both the wires are joined together in series, the total resistance becomes
Options- A. 2R
- B. R/2
- C. 5R/4
- D. 3R/4 Discuss
- 3. What is the reason for formation of Mirage in desert?
Options- A. Refraction of light
- B. Reflection of light
- C. Total internal reflection of light
- D. Both Refraction and Total internal reflection of light Discuss
- 4. The bending of light when it passes around a corner or a slit is due to ______.
Options- A. reflection
- B. refraction
- C. diffraction
- D. total internal reflection Discuss
- 5. Which one of the following is applicable to collision-coalescence process of precipitation?
Options- A. Clouds which do not extend beyond the freezing level
- B. Clouds which extend beyond the freezing level
- C. All types of clouds
- D. Cirrocumulus cloud Discuss
- 6. The pressure of a fluid varies with depth h as P = PQ+pgh, where p is the fluid density. This expression is associated with
Options- A. Pascal?s law
- B. Newton?s law
- C. Bernoulli?s principle
- D. Archimedes? principle Discuss
- 7. The group of solar cells joined together in a definite pattern is called a
Options- A. Battery
- B. Solar Heater
- C. Solar cooker
- D. Solar cell panel Discuss
- 8. It is difficult to fix a nail on a freely suspended wooden frame. Which law supports this statement?
Options- A. Law of inertia
- B. Newton's second law
- C. Newton's third law
- D. Pascal's law Discuss
- 9. Which one of the following is not a property of electromagnetic waves?
Options- A. Electromagnetic waves do not show interference and diffraction.
- B. Oscillating electric field and magnetic field are perpendicular to each other.
- C. Electromagnetic waves are transverse waves
- D. Electromagnetic waves do not require a medium to propagate. Discuss
- 10. Which of the following is a characteristic of an exothermic reaction?
Options- A. Release of heat
- B. Absorption of heat
- C. Doesn't involve any change in temperature
- D. None of the option is correct Discuss
Physics problems
Search Results
Correct Answer: scattering of light
Explanation:
According to Rayleigh's law, the intensity of scattered light varies inversely as the fourth power of its wavelength. Sunlight consists of seven colours. Of these, red has the maximum wavelength. During sunrise and sunset, the rays have to travel a larger part of the atmosphere because they are very close to the horizon.Therefore, light other than red is mostly scattered away. Most of the red light, which is the least scattered, enters our eyes. Hence, the sun and the sky appear red.
Correct Answer: 5R/4
Explanation:
So, resistance of Wire 2 is R/4 as radius is half of wire 1, so area would be 4 times of wire 1.
Now for resistance in series. R= R1 + R2.
Therefore, Final R= R + R/4 = 5R/4
Correct Answer: Both Refraction and Total internal reflection of light
Correct Answer: diffraction
Correct Answer: Clouds which do not extend beyond the freezing level
Explanation:
In colder clouds: droplets formed by Bergeron mechanism. But, in many parts of the world the air is too warm for ice crystals to form. This being the case, rain and snow cannot develop following the Bergeron Process. Instead, tiny droplets form as they collide into one another creating larger and larger droplet, this is known as collision-coalescence process. So, warmer clouds are associated with this keyword.
Correct Answer: Pascal?s law
Explanation:
Pascal's law is a principle in fluid mechanics that states that a pressure change occurring anywhere in a confined incompressible fluid is transmitted throughout the fluid such that the same change occurs everywhere.
This principle is stated mathematically as: P= P + rgh
Correct Answer: Solar cell panel
Correct Answer: Newton's third law
Correct Answer: Electromagnetic waves do not show interference and diffraction.
Correct Answer: Release of heat
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