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- Question
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
- Correct Answer
- the doped silicon piece will become p-type
Explanationp 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
- 1. What is the SI unit of temperature?
Options- A. Kelvin
- B. Joule
- C. Celsius
- D. Fahrenheit Discuss
- 2. 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 Discuss
- 3. 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
- 4. 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
- 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 Discuss
- 6. 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 Discuss
- 7. 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 Discuss
- 8. 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 Discuss
- 9. 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 Discuss
- 10. 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. Discuss
Physics problems
Search Results
Correct Answer: Kelvin
Correct Answer: Due to refraction
Correct Answer: Release of heat
Correct Answer: Electromagnetic waves do not show interference and diffraction.
Correct Answer: Newton's third law
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).
Correct Answer: 7C
Explanation:
As the capacitance is charged by the factor equal to the value of dielectric constant, Hence, C? = kC = 7C
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.
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
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.
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