Home » 2010 » August

Monthly Archives: August 2010

Wormhole

Deepa asked:

“What is a worm hole?”

Ans:

A wormhole is a hypothetical topological feature of spacetime that would be, fundamentally, a "shortcut" through spacetime.

A wormhole is, in theory, much like a tunnel with two ends each in separate points in [wiki]spacetime[/wiki]. image

There is no observational evidence for [wiki]wormholes[/wiki], but on a theoretical level there are valid solutions to the equations of the theory of general relativity which contain wormholes. The first type of wormhole solution discovered was the Schwarzschild wormhole which would be present in the Schwarzschild metric  describing an eternal black hole, but it was found that this type of wormhole would collapse too quickly for anything to cross from one end to the other. Wormholes which could actually be crossed, known as traversable wormholes, would only be possible if exotic matter with negative energy density could be used to stabilize them

Faster than light Travel
[wiki]Wormholes [/wiki]allow superluminal (faster-than-light) travel by ensuring that the speed of light is not exceeded locally at any time. While traveling through a wormhole, subluminal (slower-than-light) speeds are used. If two points are connected by a wormhole, the time taken to traverse it would be less than the time it would take a light beam to make the journey if it took a path through the space outside the [wiki]wormhole[/wiki]. However, a light beam traveling through the wormhole would always beat the traveler. As an analogy, running around to the opposite side of a mountain at maximum speed may take longer than walking through a tunnel crossing it.

Ref: Wikipedia

Indian Journal of Pure & Applied Physics (IJPAP) Browse the Latest articles published

List of Articles:

EPR study of free radicals in amino acid derivatives gamma-irradiated at 300 K
Aydin, Murat
611-614
View Full Text

FTIR study of modification of transition metal on zeolites for adsorption
Bardakçi, Belgin; Bahçeli, Semiha
615-620
View Full Text

Total ionization cross-sections of atmospheric molecules due to electron impact
Kumar, Yogesh; Tiwari, Neelam; Kumar, Manoj; Tomar, Surekha
621-625
View Full Text

Spectral editing with 2D E-HMQC NMR spectroscopy for CDn groups: A theoretical study
Şaka, İ; Gümüş, S; Gençten, A
626-631
View Full Text

Characterization of iron slag of Kakching, Manipur by X-ray and optical spectroscopy
Sheikh, M R; Acharya, B S; Gartia, R K
632-634
View Full Text

Automatic optical inspection system for the image quality of microlens array
Lin, Chern-Sheng; Ho, Chen-Wei; Yang, Shih-Wei; Chen, Der-Chin; Yeh, Mau-Shiun
635-643
View Full Text

Acoustical properties of ternary mixtures of 1-alkanols in di-isopropyl ether and 2,2,2-trifluoroethanol mixed solvent
Palani, R; Balakrishnan, S
644-650
View Full Text

Acoustic and viscosity studies of alkali metals and ammonium halides in aqueous dextran solutions at four different temperatures
Dash, U N; Roy, G S; Talukdar, M; Moharatha, D
651-657
View Full Text

Structural, thermal and optical properties of Cu2+ and Co2+: PVP polymer films
Sivaiah, K; Rudramadevi, B Hemalatha; Buddhudu, S
658-662
View Full Text

Effect of pressure and temperature on C60 fullerite
Sharma, Uma D; Joshi, H; Kumar, M
663-667
View Full Text

Microwave dielectric relaxation, thermodynamic and conformational studies of hydrogen bonded binary mixtures of propan-1-ol with methyl benzoate and ethyl benzoate
Mohan, T Madhu; Sastry, S Sreehari; Murthy, V R K
668-675
View Full Text

Use of modern telephone network for time transfer: An innovation
Thorat, Pranalee P; Banerjee, P
676-680
View Full Text

Recent Articles

Use of modern telephone network for time transfer: An innovation

Microwave dielectric relaxation, thermodynamic and conformational studies of hydrogen bonded binary mixtures of propan-1-ol with methyl benzoate and ethyl benzoate

Effect of pressure and temperature on C60 fullerite

Structural, thermal and optical properties of Cu2+ and Co2+: PVP polymer films

Acoustic and viscosity studies of alkali metals and ammonium halides in aqueous dextran solutions at four different temperatures

Question from Wave Optics

Rajat Asked:

What is the difference between interference and diffraction?

Ans:

Interference is caused by the superposition of wave fronts from two coherent sources; But diffraction is caused by the superposition of wavelets from a single wavefront when it confronts an obstacle or a slit.

Note: Visitors are requested to add to the answer through comments

Question from Rotational Dynamics

Dyana Asked:

A small rubber wheel is used to drive a large pottery wheel. The two wheels are mounted so that their circular edges touch. The small wheel has a radius of 3.5 cm and accelerates at the rate of 7.9 rad/s^2, and it is in contact with the pottery wheel (radius 23.0 cm) without slipping.
a)Calculate the angular acceleration of the pottery wheel
b)Calculate the time it takes the pottery wheel to reach its required speed  of  64 rpm

Students and teacher visitors are requested to respond

Doubt from HC Verma’s Concepts of Physics Volume I

If any one can explain step wise calculation of Example no. 17 of Chapter 2 of concepts of Physics by H C Verma Vol. 1.
Thanks in advance

Ans:

Solutions to the entire problems from concepts of Physics by HC Verma available at http://sites.google.com/site/physicsclassroomonline as well as www.plustwophysics.com

Why ordinary ammeter cannot measure AC?

Ac changes its direction frequently and therefore the ordinary ammeter which is just a galvanometer with a shunt, tends to respond to the magnitude and direction of the instantaneous values of current and in effect it will not show any deflection.
Ac is measured using hot wire ammeter, which is based on the heating effect of current

Devices using permanent magnets and electromagnets

Galvin Pinto asked;

  1. List the devices where permanent magnets & electromagnets are used.
  2. Sketch the pattern of the field lines around a current carrying:
    • Straight Conductor

    • Loop of wire

    • Solenoid

    Ans:

    1. Permanent Magnets are used in
      • Laboratory magnets
      • loud speakers
      • microphones
      • cyclotron
      • generators
      • and many more
    2. Pattern of the field lines around a current carrying

    Straight Conductor

    image

    Loop of wire

    image

    Solenoid

    image

    Visitors So Far @ AskPhysics

    • 2,046,020 hits

    Subscribe to Blog via Email

    Enter your email address to subscribe to this blog and receive notifications of new posts by email.

    Join 4,000 other subscribers

    askphysics@Twitter

    • What is a machine? https://t.co/gfnf2c9mCt https://t.co/veSGeX3OWV
      about 2 days ago
    %d bloggers like this: