Physics problems
- 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 Also asked in: Bank Exams
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.
- 2. 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 Also asked in: Bank Exams
Correct Answer: > P
Explanation:
Aluminum 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.
- 3. 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 Also asked in: Bank Exams
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
- 4. 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 Also asked in: Bank Exams
Correct Answer: Solar cell panel
- 5. 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 Also asked in: Bank Exams
Correct Answer: Newton's third law
- 6. 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. Also asked in: Bank Exams
Correct Answer: Electromagnetic waves do not show interference and diffraction.
- 7. 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 Also asked in: Bank Exams
Correct Answer: Release of heat
- 8. Why does water tank appear shallower when viewed from the top?
Options- A. Due to reflection
- B. Due to refraction
- C. Due to diffraction
- D. Due to total internal reflection Also asked in: Bank Exams
Correct Answer: Due to refraction
- 9. What is the SI unit of temperature?
Options- A. Kelvin
- B. Joule
- C. Celsius
- D. Fahrenheit Also asked in: Bank Exams
Correct Answer: Kelvin
- 10. When a piece of pure silicon is doped with aluminium, then
Options- A. the conductivity of the doped silicon piece will remain the same
- B. the doped silicon piece will become n-type
- C. the doped silicon piece will become p-type
- D. the resistivity of the doped silicon piece will increase Also asked in: Bank Exams
Correct Answer: the doped silicon piece will become p-type
Explanation:
p type of semiconductor is obtained when Silicon is doped with a trivalent impurity like Aluminium. Aluminium is a p-type dopant, which means that when a semiconductor i.e. silicon is doped with aluminium, it creates a hole (positively charged carrier) by accepting an electron from the silicon atom. Electrical conductivity of semiconductors increasesand resistivity remains the same
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