Physics problems
- 1. Suppose voltage V is applied across a resistance R. The power dissipated in the resistance is P. Now the same voltage V is applied across a parallel combination of three equal resistors each of resistance R. Then the power dissipated in the second case will be
Options- A. P
- B. 3P
- C. p/3
- D. 2p/ 3 Also asked in: Bank Exams
Correct Answer: 3P
Explanation:
P= I^2.R where, I= Current, P= Electric Power, R=Resistance. Here all the resistance is put in parallel combination and in parallel combination the value of Resistance decreases and dissipation of power increase, hence 3 times more power will be dissipated(3P).
- 2. A parallel-plate capacitor,with air in between the plates, has capacitance C. Now the space between the two plates of the capacitor is filled with a dielectric of dielectric constant 7. Then the value of the capacitance will become
Options- A. C
- B. C/7
- C. 7C
- D. 14C Also asked in: Bank Exams
Correct Answer: 7C
Explanation:
As the capacitance is charged by the factor equal to the value of dielectric constant, Hence, C? = kC = 7C
- 3. For which one of the following does the centre of mass lie outside the body?
Options- A. A fountain pen
- B. A cricket ball
- C. A ring
- D. A book Also asked in: Bank Exams
Correct Answer: A ring
Explanation:
For balancing the weight of ring, you need to put your finger or any solid object inside the ring so that you will be able to sustain their own weight because they are not able to sustain their own weight.so its centre of mass lies outside the body.
- 4. A parallel-plate capacitor of capacitance C1is made using two gold plates. Another parallel-plate capacitor of capacitance C2is made using two aluminium plates with same plate separation, and all the four plates are of same area. If g?and aPare respectively the electrical resistivities of gold and aluminium, then which one of the following relations is correct?
Options- A. C1>C2
- B. C2>C1
- C. C1pa = C2pg
- D. C1 = C2 Also asked in: Bank Exams
Correct Answer: C1 = C2
Explanation:
C1= capacitance of gold plates
C2= capacitance of aluminium plates
rg= Gold?s resistivity
ra= Aluminium?s resistivity
As the capacitance depends on the shape, size & geometrical placing of the conductors & the medium between them, hence, the value of capacitance will be independent of resistivity. Therefore, C1= C2
- 5. A photon of X-ray has energy of 1 keV. A photon of visible radiation has energy of 3 eV. In this context, which one of the following statements is not correct?
Options- A. The wavelength of X-ray photon is less than the wavelength of visible radiation photon.
- B. Both the photons have different energies.
- C. The speeds of both the photons in vacuum are different
- D. The frequency of X-ray photon is higher than the frequency of visible radiation photon. Also asked in: Bank Exams
Correct Answer: The speeds of both the photons in vacuum are different
Explanation:
The speed of all the electromagnetic radiation are always same and equal to the numerical value 3 x 10^8m/sec.
- 6. Which one of the following statements with regard to Jet stream, an upper level tropospheric wave, is not correct?
Options- A. It is narrow band of high-velocity wind.
- B. It follows the wave path near the tropopause at elevations of 8 km to 15 km.
- C. Jet streams are typically continuous over long distances.
- D. In summer, the polar front jet achieves its maximum force. Also asked in: Bank Exams
Correct Answer: It follows the wave path near the tropopause at elevations of 8 km to 15 km.
Explanation:
All are correct except D, as Jet streams are phenomena of winter. It is believed that jet stream exercises an important influence on the winter weather in India.
- 7. Which phenomena shows the particle nature of light?
Options- A. Diffraction
- B. Interference
- C. Photoelectric effect
- D. Polarisation Also asked in: Bank Exams
Correct Answer: Photoelectric effect
- 8. On which principle does the hydraulic lift works?
Options- A. Newton's law
- B. Pascal's law
- C. Archimedes's law
- D. Joule's law Also asked in: Bank Exams
Correct Answer: Pascal's law
- 9. What is the process of conversion of solid state directly to gaseous state called?
Options- A. Evaporation
- B. Condensation
- C. Sublimation
- D. Distillation Also asked in: Bank Exams
Correct Answer: Sublimation
- 10. Supercooling is cooling of liquid _____.
Options- A. below melting point
- B. below freezing point
- C. at melting point
- D. above melting point Also asked in: Bank Exams
Correct Answer: below freezing point
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