Recent questions tagged sec-e

a)Give the mechanism of preparation of ethoxy ethane from ethanol b) Alcohols act as weak bases . explain .

asked Oct 13, 2016 by meena.p

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How long an electric lamp of $100 w$ be kept glowing by fusion of $2.0\;kg$ of deuterium ?

asked Aug 3, 2016 by meena.p

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The work function for the following metals is given $Ni: 5.15 \; ev$ What happen if the laser is brought never and placed 50 cm away ?

asked Jun 28, 2016 by meena.p

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A mercury lamp is a convenient source for studying frequency dependence of photo electric emission , Since it gives a number of spectral lines rating from the uv to the red end of the visible spectrum . In our experiment with rubidium photo- cell , the following lines from a mercury source where used . $ \lambda_1 = 3650 A^{\circ}, \lambda_2 = 4047 A^{\circ}, \lambda_1 = 4358 A^{\circ}, \lambda_4 = 5461 A^{\circ}, \lambda_5 = 6907 A^{\circ}$The stopping voltages respectively were measured to be : $V_{o1}= 1.28 \;v , V_{o2}= 0.95 \;v, V_{o3}= 0.74 \;v, V_{o4}= 0.16\;v, V_{o5}= 1.28 \;v$ Estimate the threshold frequency and work function for the material .

asked Jun 27, 2016 by meena.p

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A mercury lamp is a convenient source for studying frequency dependence of photo electric emission , Since it gives a number of spectral lines rating from the uv to the red end of the visible spectrum . In our experiment with rubidium photo- cell , the following lines from a mercury source where used . $ \lambda_1 = 3650 A^{\circ}, \lambda_2 = 4047 A^{\circ}, \lambda_1 = 4358 A^{\circ}, \lambda_4 = 5461 A^{\circ}, \lambda_5 = 6907 A^{\circ}$The stopping voltages respectively were measured to be : $V_{o1}= 1.28 \;v , V_{o2}= 0.95 \;v, V_{o3}= 0.74 \;v, V_{o4}= 0.16\;v, V_{o5}= 1.28 \;v$ Determine the value of plark's constant be

asked Jun 27, 2016 by meena.p

1 answer

Monochromatic radiation of wave length $640.2 nm$ from a neon lamp irradiates a photo sensitive material made of calcium or tungsten. The stopping voltage is mentioned to be $0.54\;v$ . The source is replaced by an iron source and its $427.2\;nm$ line irradiates the same photo cell . predict the new stopping voltage .

asked Jun 27, 2016 by meena.p

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Estimate the speed with which electron emitted from a heated cathode of an evacuated tube impinge on the anode maintained at a potential difference of $500\;v$ , with respect to the cathod . Ignore the small initial speeds of the electrons . The specific charge of the electron (ie) its $\large\frac{e}{m}$ is given to be $1.76 \times 10^{11}\;kg^{-1}$ use the same formula you employ to obtain electron speed for an anode potential of 10 Mv. Do you see what is wrong ? In what way in is the formula to be modified ?

asked Jun 24, 2016 by meena.p

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(i) Find the magnitude and direction of current in $1 \Omega$ resistor in the given circuit . (ii) Two students X and Y perform an experiment on potentio meter separately using the circuit diagram shown below. Keeping other things unchanged (a) X increases the value of resistance R, (b) Y decrease the value of resistance S in the set up. How will these change affect the position of null point in each case and why ? (a) Use Kirchhoff's rules , calculate the current in the arm AC of the given circuit ? (b) On what principle does the meter bridge work ? Why are the metal strips used in the bridge ?

asked Jun 10, 2016 by meena.p

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Draw a ray diagram showing the geometry of formation of image of a point object situated on the principal axis and on the convex side of a spherical surface of radius of curvature R. Taking the rays as incident from a rarer medium of refractive index $n_1$ to a denser medium of refractive index $n_2$ derive the relation. $\large\frac{n_@}{v} -\frac{n_1}{u} = \frac{n_2-n_1}{R}$, Where symbols have their usual meaning ? (ii) Explain briefly how the focal length of a convex lens changes with increase in wave length of incident light . (iii) What happens to the focal length of convex lens when it is immersed in water ? Refractive index of the material of lens is greater than water .

asked Jun 9, 2016 by meena.p

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When a parallel beam of monochromatic source of light of wave length incident on a single slit of width, show how the diffraction pattern is formed at the screen by the interference of the wavelets from the slit.

asked Jun 9, 2016 by meena.p

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(a) Consider a beam of charged particles moving with varying speeds.Show how crossed electric and magnetic fields can be used to select charged particles of a particular velocity ? (b) Name another device / machine do and what are the functions of magnetic and electric fields in this machine ? Where do these exists in this machine ? Write about their natures .

asked Jun 9, 2016 by meena.p

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Express Biot-savart law in the vector form. (ii) Use it to obtain the expression for the magnetic field at an axial point, distance d from the center , of a circular coil of radius R carrying current I. (iii) Also , find the ratio of the magnitudes of the magnetic field of this coil at the center at an axial point for which $x= R\sqrt 3$

asked Jun 9, 2016 by meena.p

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Derive an expression for the electric field intensity at a point on the equatorial line of an electric dipole moment $\overrightarrow{P}$ and length 2a. What is the direction of this field ?

asked Jun 9, 2016 by meena.p

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(i) Name the phenomenon on which the working of an optical fiber is based ? (ii) What are the necessary condition for this phenomenon to occur ?

asked Jun 9, 2016 by meena.p

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(i) For a glass prism $(\mu = \sqrt 3 )$ the angle of minimum deviation is equal to the angle of the prism. Calculate the angle of the prism . (ii) Draw ray diagram when incident ray falls normally on one of the two equal sides of a right angled isosceles prism having refractive index $\mu = \sqrt 3$

asked Jun 8, 2016 by meena.p

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(a)Define the term "intensity of radiation " in photon picture. (b) . plot a graph showing the variation of photo current vs collector potential for three different intensities $I_1 > I_2 > I_3$, two of which $(I_1$ and $I_2)$ have the same frequency v and the third has frequency $v_1 > v$ (c) Explain the nature of the curves on the basis of Einstein's equation .

asked Jun 8, 2016 by meena.p

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Draw a circuit diagram of a common emitter amplifier using n-p-n transistor . Derive an expression for the current gain $\beta _{ac}$

asked Jun 8, 2016 by meena.p

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Plot a graph showing the variation of binding energy per nucleon as a function of mass number. Which property of nuclear force explains the approximate constancy of binding energy in the range $30 < A < 170$ ? How does one explain the release of energy in both the processes of nuclear fission from the graph ?

asked Jun 8, 2016 by meena.p

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Plot a graph showing the variation of binding energy per nucleon as a function of mass number. Which property of nuclear force explains the approximate constancy of binding energy in the range $30 < A < 170$ ? How does one explain the release of energy in both the processes of nuclear fission from the graph ?

asked Jun 8, 2016 by meena.p

1 answer

Derive an expression for the axial magnetic field of a finite solenoid of length 2l and radius r carrying current I. Under what condition does the field become equivalent to that produced by a bar magnet ?

asked Jun 8, 2016 by meena.p

1 answer

(i) Mention two properties of soft iron due to which is preferred for making an electromagnet ? (ii) State Gauss's law in magnetism. How is it different from Gauss's law in electrostatics and why ?

asked Jun 8, 2016 by meena.p

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Three identical capacitors each of capacitance $3 \mu F$ are connected in term in series and in parallel combination to the common source of V volt . find out the ratio of the energies stored in two configurations.

asked Jun 7, 2016 by meena.p

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A parallel plate capacitor $(C_1)$ having charge Q is connected to an identical uncharged capacitor $C_2$ in series. What would be the charge accumulated on the capacitor $C_2$?

asked Jun 7, 2016 by meena.p

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Mention any three applications of the internet. explain one of these in detail .

asked Jun 7, 2016 by meena.p

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A capacitor of unknown capacitance,a resistor of $100 \Omega$ and an inductor of self inductance $L= (4/\pi ^2)$ hentry are connected in series to an ac source of 200 V and 50 Hz. Calculate the value of the capacitance and impedance of the circuit When the current is in phase with the voltage. Calculate the power dispersal in the circuit .

asked Jun 7, 2016 by meena.p

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(i) Explain briefly the process of emanation of light by light emitting Diode (LED). (ii) Which semiconductor are provided to make LED and why ? (iii) Give two advantages of using LED over conventional incandescent lamps

asked May 30, 2016 by meena.p

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Two harmonic waves of monochromatic light : $y_1$ = n const and $y_2 =a \cos (wt + \phi)$ are superimposed on each other. Show that maximum intensity in interference pattern is four times the intensity due to each slit. Hence write the condition for constructive and destructive interference in terms of the phase angle $\phi $

asked May 30, 2016 by meena.p

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In Young's double slit experience using monochromatic light of wave length $\lambda$ , the intensity of light at a point on the screen where path different is $\lambda$ is k units. What is the intensity at a point where path different is $\large\frac{\lambda}{3}$

asked May 26, 2016 by meena.p

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At what angle should a ray of light be incident on the face of a prism of refracting angle $60^{circ}$ , So that it just suffers total internal reflection at the other face ? The refractive index of the prism is $1.524$

asked May 17, 2016 by meena.p

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An object 1.5 cm in placed on the side of the convex lens, where two lenses of focal lengths 30 cm and 20 cm are placed 8.0 cm apart with their principle axis coincident . The distance between the object and the convex lens is 40 cm. Determine the magnification produced by two lens system and size of the image

asked May 17, 2016 by meena.p

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Determined the effective focal length of the combination of two lenses of focal length 30 cm and 20 cm if they are placed 8.0 cm apart with their principal axes coincident. Does the answer depend on which side a beam a parallel light is incident ? Is the motion of effective focal length of system useful at all ?

asked May 17, 2016 by meena.p

1 answer

What is the focal length of a convex lens of focal length 30 cm in contact with a concave lens of focal length 20 cm. Is the system a converging or a diverging less ? Ignore the thickness of the thickness of the lenses

asked Mar 3, 2016 by meena.p

1 answer

An object of size $3.0\;cm$ is placed 14 cm in front of a concave lens of focal length $21\;cm$. Describe the image produced by the less. What happens if the object is moved further from the less ?

asked Mar 3, 2016 by meena.p

1 answer

An object of size $3.0\;cm$ is placed 14 cm in front of a concave lens of focal length $21\;cm$. Describe the image produced by the less.

asked Mar 3, 2016 by meena.p

1 answer

A multi range current meter can be constructed by using a galvanometer circuit as shown in figure . We want a current meter that can measure $10\;mA,100\;mA$ and $1\;A$ using a galvanometer of resistance $10 \Omega$ and that produces maximum deflection for current $1\;mA$ Find $S_1,S_2$ and $S_3$ that have to be used

asked Aug 3, 2015 by meena.p

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When an electric dipole of moment $|P|=q \times 2a$ is held at an angle $\theta$ with the direction of uniform external field E, a torque $T= PE \sin \theta$ acts on the dipole. This torque tries to align the electric dipole in the direction of the field. When P is along E $\theta =0^{\circ} , t= PE \sin 0=zero$ What is the direction of torque acting on electric dipole held at an angle with uniform electric field?

asked Apr 29, 2015 by meena.p

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Suppose the particle in $Q_{33}$ is an electron projected with velocity $V_x =2.0 \times 10^6 m/s$. If E between the plates separated by $0.5 \;cm$ is $9.1 \times 10^2 N/C$, where will the electron strike the upper plate ? $(|e|=1.6 \times 10^{-19}\;C,m_e=9.1 \times 10^{-3}\;kg)$

asked Apr 29, 2015 by meena.p

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A particular of mass m and charge $(-q)$ enters the region between the two charged plates initially moving along x-axis with speed $V_x $ (like particle 1 in the figure) . The length of plate of L and a uniform electricity field E is maintained between the plates. she that the vertical deflection of the particle at the fan edge of the plate is 4qEl^2/2mv_x ^2$. Compare this motion with motion of a projectile in gravitational field.

asked Apr 29, 2015 by meena.p

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Consider an arbitrary electrostatic field configuration . A small test charge is placed at a null point . ( i.e where $E=0$)of the configuration . Show that the equilibrium of the test charge is necessarily unstable .

asked Apr 29, 2015 by meena.p

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It is believed that protons and neutrons (which constitute nucli of or ordinary matter) are themseleves built out of more elementary units called quarks. A proton and a neutron consists of there quarks each. Two type of quarks, the so called 'up' quark (denoted by u) of charge $+\bigg( \large\frac{2}{3}$$e\bigg)$ and the down quark denoted by of charge $\bigg( \large\frac{-1}{3}$$e\bigg)$, together with electricity build up an ordinary matter. (quarks of other types have also been found which give rise to different ususual varieties of matter. ). Suggest a possible quark composition of a proton and neutron .

asked Apr 29, 2015 by meena.p

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A conductor A with a cavity as shown in the fig(a) is given a charge Q. Show that the entire charge must appear on the outer surface of the conductor .

asked Apr 28, 2015 by meena.p

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As oil drop of 12 excess electron is held stationary under a constant electric field of $2.55 \times 10^4 \;N/C$ in Millikan's oil drop experiment . The density of the oil is $ 1.26\;g/cm^3$ Estimate the radius of the drop . $(g = 9.8 \;m/s^2; e = 1.60 \times 10^{-91}\;C)$

asked Apr 28, 2015 by meena.p

1 answer

The electric field component in the following figure are $Ex = \alpha x^{1/2}, E_y =0, E_z=0$ in which $\alpha =800 NCm6{-1/2}$ Calculate the charge within the cube. Assume $a= 0.1\;m$

asked Apr 28, 2015 by meena.p

1 answer

The electric field component in the following figure are $Ex = \alpha x^{1/2}, E_y =0, E_z=0$ in which $\alpha =800 NCm6{-1/2}$ Calculate the flux $\phi _2$ through the cube

asked Apr 28, 2015 by meena.p

1 answer

Two points charges $q_1$ anb $ q_2$ are located at points $(a,0,0)$ and $(0,b,0)$ respectively . Find the electric field bue to these charges at the point $(0,0,0)$

asked Apr 28, 2015 by meena.p

1 answer

Two large thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and magnitude $17.0 \times 10^{-22}C/m^2$ what is E? between the plates ?

asked Apr 28, 2015 by meena.p

1 answer

Two large thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and magnitude $17.0 \times 10^{-22}C/m^2$ what is E? In the outer region of the second plate ?

asked Apr 28, 2015 by meena.p

1 answer

Two large thin metal plates are parallel and close to each other. On their inner faces, the plates have surface charge densities of opposite signs and magnitude $17.0 \times 10^{-22}C/m^2$ what is E? In the outer region of the first plate ?

asked Apr 28, 2015 by meena.p

1 answer

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