Recent questions in Physics

A parallel plate capacitor is made by stacking $n$ equally spaced plates connected alternatively. If the capacitance between any two adjacent plates is C then the resultant capacitance is

asked Feb 15, 2014 by thanvigandhi_1

1 answer

A heater coil is cut into two equal parts and only one part is now used in the heater. The heat generated will now be

asked Feb 15, 2014 by thanvigandhi_1

1 answer

Two sources of equal emf are connected to an external resistance R. The internal resistance of the two sources are $R_1\: and \: R_2 (R_2 > R_1)$. If the potential difference across the source having internal resistance $R_2$ is zero then,

asked Feb 15, 2014 by thanvigandhi_1

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In the circuit the galvanometer $G$ shows zero deflection. If the batteries A and B have negligible internal resistance, the value of the resistor $R$ will be

asked Feb 15, 2014 by thanvigandhi_1

1 answer

Two voltameters one of copper and other of silver, are joined in parallel. When a total charge $q$ flows through a voltameters, equal amount of metals are deposited. If the electrochemical equivalents of copper and silver are $z_1\: and \: z_2$ respectively the charge which flows through the silver voltameter is

asked Feb 15, 2014 by thanvigandhi_1

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A moving coil galvanometer has 150 equal divisions. Its current sensitivity is 10 divisions per milliampere and voltage sensitivity is 2 divisions per millivolt. In order that each division reads 1 volt, the resistance in ohms needed to be connected in series with the coil will be

asked Feb 15, 2014 by thanvigandhi_1

1 answer

Let $ \varepsilon_0$ denote the dimensional formula of the permittivity of vacuum. If M = mass, L = length and T = time and A = electric current then,

asked Feb 15, 2014 by thanvigandhi_1

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In an LCR circuit as shown below both switches are open initially . Now switch $S_1$ is closed $S_2$ kept open. ( q is charge on the capacitor and $\tau = RC$ is capacitive time constant ) which of the following statement is correct ?

asked Feb 15, 2014 by thanvigandhi_1

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What is the dimensional formula for inductance?

asked Feb 15, 2014 by thanvigandhi_1

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What is the dimensional formula for capacitance?

asked Feb 15, 2014 by thanvigandhi_1

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What is the dimensional formula for resistivity?

asked Feb 15, 2014 by thanvigandhi_1

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A 5V battery with internal resistance $2\Omega$ and a 2V battery with internal resistance $1\Omega$ are connected to a $ 10 \Omega $ resistor as shown in the figure. The current in the $ 10\Omega $ resistor is

asked Feb 15, 2014 by thanvigandhi_1

1 answer

An equi - convex lens of crown and equi convex lens of flint glass make an achromatic system. The radium of curvature of convex lens is $0.54\;m$. If the focal length of combination for mean colour is 1.5 m and $RI$ for crown glass are $\mu _R= 1.53$ and $\mu_v =1.55$ Then the dispersive power of flint glass is

asked Feb 14, 2014 by meena.p

1 answer

Consider a block of conducting material of resistivity $ \rho$ shown in the figure. Current I enters at A and leaves from D. We apply superposition principle to find voltage $ \Delta V$ developed between B and C. The calculation is done in the following steps. \[\] (i) Take current I entering from A and assume it to spread over a hemispherical surface in the block. \[\] Calculate field E(r) at distance r from A by using ohm's law $E= \rho j$, where j is the current per unit area at r. \[\] (iii) From the r dependence of E(r) obtain the potential V(r) at r. \[\] (iv) Repeat (i), (ii) and (iii) for current I leaving D and superpose results for A and D \[\] For current entering at A, the electric field at a distance r from A is

asked Feb 14, 2014 by thanvigandhi_1

1 answer

Consider a block of conducting material of resistivity $ \rho$ shown in the figure. Current I enters at A and leaves from D. Apply the superposition principle and find the voltage $ \Delta V$ developed between B and C?

asked Feb 14, 2014 by thanvigandhi_1

1 answer

In a YDSE $\lambda =60 \;nm\; D= 2m\;\lambda=6 mm$. Find the positions of a point lying b/w third maxima and third minima where the intensity in three - fourth of maximum intensity on the screen .

asked Feb 14, 2014 by meena.p

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When the screen is moved away from plane of slits in YDSE then the effect on interference fringes is

asked Feb 14, 2014 by meena.p

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In an interference arrangement similar to YDSE , Slits $S_1\;and \;S_2$ are illuminated with coherent microwave sources and are synchronized to have zero phase difference The slits are separates by distance $d= 150 \;m$. The intensity $I_0$ is measured as a function of $\theta$ where $\theta$ is defined as shown. If $I _0$ is max intensity, calculate $I_0$ for $\theta=90^{\circ}$

asked Feb 14, 2014 by meena.p

1 answer

A parallel plate capacitor with air between the plates has a capacitance of $9\: pF$. The separation between the plates is $d$ . The space between the plates is now filled with two dielectrics. One of the dielectrics has dielectric constant $k_1=3$ and thickness $ \large\frac{d}{3}$ while the other has dielectric constant $k_2=6$ and thickness $ \large\frac{2d}{3}$. Capacitance of the capacitor is now

asked Feb 14, 2014 by thanvigandhi_1

1 answer

Shown in the figure below is a meter-bridge setup with null deflection in the galvanometer.The value of the unknown resistor $R$ is

asked Feb 14, 2014 by thanvigandhi_1

1 answer

A thin plano- convex lens of focal length f is split into two halves one of halves is shifted along the optical axis. The separation b/w object and image plane is 1.8 m. The magnification of image formed by one of half lenses is 2. Find the focal length of lens and separation b/w the two halves.

asked Feb 14, 2014 by meena.p

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Calculate the effective resistance between points A and B

asked Feb 14, 2014 by thanvigandhi_1

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What is the average drift speed of conduction electrons in a copper wire of cross-sectional area $1.0 \times 10^{–7}m^2$ carrying a current of $1.5 A$. Assume that each copper atom contributes roughly one conduction electron. The density of copper is $ 9.0 \times 10^3 kg/m^3 $ , and its atomic mass is $ 63.5 u.$

asked Feb 14, 2014 by thanvigandhi_1

1 answer

The cross section of glass prism has the form of an isosceles triangle . One of equal face is silvered. A ray of light incident normally on other equal face and after being reflected twice, emerges through base of prism along normal. That the angle of prism is :-

asked Feb 14, 2014 by meena.p

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At what temperature would the temperature of a copper conductor be double its value at $0^{\circ}C\: \alpha_{Cu} = 4 \times 10^{-3}$

asked Feb 14, 2014 by thanvigandhi_1

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Which of the following is an example of ohmic conductor:

asked Feb 14, 2014 by thanvigandhi_1

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Two identical charged spheres are suspended by strings of equal length . The strings make an angle of $\;60^{0}\;$ with each other . When suspended in a liquid of density $\;0.5 g/cc,\;$ the angle remains the same . The dielectric constant of the liquid is [density of material of sphere is $\;1.5 g/cc\;$]

asked Feb 14, 2014 by yamini.v

2 answers

A lens has a power of +5 diopter in air what will be its power if completely immersed in water ? $ \mu_g =\large\frac{3}{2};$$ \mu_w=\large\frac{4}{3}$

asked Feb 14, 2014 by meena.p

1 answer

A point source of light is placed at the bottom of a tank containing a liquid $(R.I= \mu)$ upto a depth $h$. A bright circular spot is seen on the surface of the liquid. Then the radius of this bright spot.:

asked Feb 14, 2014 by meena.p

1 answer

In the figure shown for an angle of incidence i at the top surface , What is the minimum refractive index needed for total internal reflection at vertical face ?

asked Feb 14, 2014 by meena.p

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A particle of mass m and charge +q is projected from the origin with a speed v at an angle $\;30^{0}\;$ with the horizontal into an electric field of intensity E directed downward . Equation of trajectory of particle is . Neglect gravity

asked Feb 14, 2014 by yamini.v

1 answer

A particle of charge -q and mass m moves in a circle of radius r arround an infinitely long line charge of linear density $\;+\lambda\;$ . Then time period will be

asked Feb 14, 2014 by yamini.v

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Three concentric spherical metallic shells A , B and C of radii a , b and c $\;(a < b < c)\;$ have charge densities $\;\sigma , - \sigma \; and \; \sigma\;$ respectively . If the shells A and C are at the same potential then the relation between a , b and c is

asked Feb 14, 2014 by yamini.v

1 answer

A 10.0 Kg block carrying a charge 100 $\;\mu C\;$ is connected to a spring for which $\;K=100 N/m\;$ . The block lies on a frictionless horizontal track , and the system is immersed in a uniform electric field $\;E=5\times10^{5}\;V/m\;$ , directed as shown in figure . If the block is released from rest when the spring is amount does the spring expand

asked Feb 14, 2014 by yamini.v

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A point charge q is placed on the top of a cone of serni-vertex angle $\;\theta\; $ Find the electric flux through the base of the cone

asked Feb 14, 2014 by yamini.v

1 answer

The current in the primary circuit of a potentiometer is $0.2 A$. The specific resistance and cross-section of the potentiometer wire are $4 \times 10^{-7} ohm $ meter and $8 \times 10^{-7} \: m^2$ respectively. The potential gradient will be equal to:

asked Feb 13, 2014 by thanvigandhi_1

1 answer

If $400ohms $ of resistance is made by adding four $ 100 \: ohm $ resistances of tolerance 5%, then the tolerance of the combination is:

asked Feb 13, 2014 by thanvigandhi_1

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Time constant of a $RC$ circuit is $2/ln(2) s$. Capacitor is discharged at time $ t = 0$. The ratio of charge on the capacitor at time $t = 2s$ and $t = 6s$ is

asked Feb 13, 2014 by thanvigandhi_1

1 answer

The potential difference across the terminals of the battery (with $2\;ohms$ internal resistance) is

asked Feb 13, 2014 by thanvigandhi_1

1 answer

The current passing through the $ 3\Omega$ resistor is

asked Feb 13, 2014 by thanvigandhi_1

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Under what conditions, can the current passing through the resistance R be increased? r1 and r2 are the internal resistances of the two batteries.

asked Feb 13, 2014 by thanvigandhi_1

1 answer

In a modified YDSE a monochromatic uniform and parallel beam of light of wavelength 6000 A and intensity $\bigg(\large\frac{10}{\pi}\bigg) \large\frac{w}{m^2}$ is incident normally on two circular operates A and B of radii $0.001\;m $ and $0.002\;m$ respectively. A perfectly transparent film of thickness $2000 A^{\circ}$ and refractive index $1.5 $ for wavelength $6000\;A^{\circ}$ is placed in front of aperture A. Calculate the pour (in waters) received at Focal spot F of lens. The lens is symmetrically placed with respect to aperture. Assume $10 \%$ of power received by each aperture goes in original direction and is bought to focal speet.

asked Feb 13, 2014 by meena.p

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An inductor of inductance $ L = 400\: mH$ and resistors of resistances $R1 = 2\Omega$ and $R2 = 2\Omega$ are connected to a battery of $emf\: 12V$ as shown in the figure. The internal resistance of the battery is negligible. The switch $K$ is closed at $t= 0$. The potential drop across $L$ as a function of time is

asked Feb 13, 2014 by thanvigandhi_1

1 answer

Two points $P$ and $Q$ are maintained at the potentials of $10V$ and $-4V$ respectively. The work done in moving $100$ electrons from $P$ to $Q$ is

asked Feb 13, 2014 by thanvigandhi_1

1 answer

Two conductors have the same resistance at $0^{\circ} C$ but their temperature coefficients of resistance are $ \alpha 1 \: and \: \alpha 2$. The temperature coefficient for the parallel combination is

asked Feb 13, 2014 by thanvigandhi_1

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Two conductors have the same resistance at $0^{\circ}C$ but their temperature coefficient of resistance are $ \alpha 1\: and \: \alpha 2$. The temperature coefficient for the series combination is

asked Feb 13, 2014 by thanvigandhi_1

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A beam of light consisting of two wavelength $6500 A^{\circ}$ and $5200 A^{\circ}$ is used to obtain interference fringes in a young's double slit exp. Then what is the distance from central maxima where the bright fringes due to both wavelength coincides? The distance between slits is 2 mm and distance between plane of slits and screen is 120 cm

asked Feb 13, 2014 by meena.p

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In the circuit shown below, the key K is closed at $ t = 0$. The current through the battery is

asked Feb 13, 2014 by thanvigandhi_1

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The intensity of an electric field depends on the coordinates x and y as follows $\;\overrightarrow{E}=\large\frac{a\;(x \hat{i} + y \hat{j})}{x^2+y^2}\;$ where a is constants. Find the charge within a sphere of radius R with the centre at the origin

asked Feb 13, 2014 by yamini.v

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A 4 cm thick layer of water covers 6 cm thick glass slab. A coin is placed at the bottom of slab and is being observed from the air side along the normal to surface. Then the apparent position of coin surface is

asked Feb 13, 2014 by meena.p

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