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A stepdown transformer is connected to main supply 200 V to operate a 6V, 30W bulb. The current in primary is
The closest distance of approach of an α - particle travelling with a velocity 'V' to a certain nucleus is 'x'. The distance of closest approach of α - particle travelling with a velocity 3V to the same nucleus is
Moseley's law states that
The frequency of characteristic X-ray spectral line is directly proportional to the square of atomic number of target element.
⇒ v ∝ Z2 i . e . √v ∝ Z
o r √v = a (z − b )
Here a is constant of proportionality b is screening constant.
An air capacitor of capacity C = 10μ F is connected to a constant voltage battery of 12 volt. Now the space between the plates is filled with a liquid of dielectric constant 5. The charge that flows now from battery to the capacitor is
C = 10 μ F
Charge in capacitor q = CV
= 10 x 12
= 120 μ C
On keeping liquid of dielectric constant5, capacity will becomes of 5 time.
∴ Charge q = 5 x 120
= 600 μ C
In connection with chemical effect of current, Faraday constant is equal to
E ∝ z or E = Fz or F = E/z
Where E = chemical equivalent
z = electrochemical equivalent
In short wave communication waves of which of the following frequencies will be reflected back by the ionospheric layer having electron density 1011 per m-3?
An electric motor operates on a d.c. source of e.m.f. V and internal resistance R. The power output of the source is maximum when the current drawn by the motor is
The electrical resistance of a mercury column in a cylindrical container is R. When the same mercury is poured into another cylindrical container twice the radius of cross-section, the resistance of mercury column now is
Two wires of the same material are given. The first wire is twice as long as the second and has twice the diameter of the second. The resistance of the first will be
Uncertainty in position of the electron is of the order of de-Broglie wavelength. Making use of Heisenberg's uncertainty principle, it will be found that uncertainty in velocity ν is of the order of
In a pure inductive circuit with a.c. source, the current lags behind e.m.f. by
When the no. of turns in a coil is triplled, without any change in the length of coil, its self-inductance becomes
A point charge q is placed at a distance a/2 directly above the centre of a square of side a. The electric flux through the square assuming it to be one face of the cube is
Equal charges are given to two conducting spheres of different radii. The potential will
Potential energy of two equal positive charges 1 μ C each held 1 m apart in air is
The electric field inside a sphere which carries a charge density proportional to the distance from the origin ρ = αr (α is a constant) is
Two capacitors of capacitances 3 μF and 6 μF are charged to a potential of 12 V each. They are now connected to each other, with the positive plate of each joined to the negative plate of the other. The potential difference across each capacitor will be
Figure shows two large cylindrical shells having uniform linear charge densities + λ and - λ . Radius of inner aylinder is 'a' and that of outer cylinder is 'b'. A charged particle of mass m , charge q revolves in a circle of radius r. Then its speed 'V' is:
[Neglect gravity and assume the radii of both cylinders to be very small in comparison to their length]
A current of 2 ampere flows in a long, straight wire of radius 2 mm. The intensity of magnetic field at the axis of the wire is
In a radioactive disintegration, the ratio of initial number of atoms to the number of atoms present at an instant of time equal to its mean life is
A heavy nucleus at rest breaks into two fragments which fly off with velocities 8:1. The ratio of radii of the fragments is
A nuclear reactor has a power of 16 Kw. If the energy per fission is 200 MeV, the number of fissions per second is
The slope of frequency of incident light and stopping potential for a given surface will be
Light of wavelength 5000 Å falls on a sensitive plate with photoelectric work function of 1.9 eV. The kinetic energy of the photoelectron emitted will be
If convex lens of focal length 80 cm and a concave lens of focal length 50 cm are combined together, what will be their resulting power?
If the two ends p and n of a p-n diode junction are joined by a wire
When the forward bias voltage increases what happens to the potential barrier.
In p-type semiconductor, majority current carriers are
In p-type semiconductor the majority charge carriers are
Electronic configuration of germanium is 2, 8, 18 and 4. To make it extrinsic semiconductor small quantity of antinomy is added
A ray of light falls on a transparent glass slab of refractive index 1.62. If the reflected ray and the refracted ray are mutually perpendicular, the angle of incidence is
An astronout is looking on earth's surface from a sapce shuttle at an altitude of 500 km. Assuming that the astronaut's pupils' diameter is 5 mm and the wavelength of visible light is 500 nm, the astronaut will be able to resolve linear objects of the size of about
Which of the following phenomena establish the wave nature of light?
Two slits, 4 mm apart, are illuminated by light of wavelength 6000 Å. What will be the fringe width on a screen placed 2 m from the slits?
When 3,3-Dimethyl-2-butanol is heated with H₂SO₄, the major product obtained is
In aldehydes and ketones, carbon of the carbonyl group is
An alkane C7H16 is produced by the reaction of Lithium di (3-pentyl) cuperate with ethyl bromide. The structural formula of product is
Complete combustion of 0.858 g of compound X gives 2.63 g of CO₂ and 1.28 g of H₂O. The lowest molecular mass X can have
Which law directly explains the law of conservation of mass?
Element found in plant systems which forms an important constituent of photosynthesis is
Methyl acetate will be obtained by reacting CH₃OH with
Hydrolytic reaction of fats by caustic soda is known as
A and B are gaseous substances which react reversibly to give two gaseous substances C and D,accompanied by the liberation of heat.When the reaction reaches equilibrium,it is observed that Kp = Kc.The equilibrium cannot be disturbed by
The facor which changes equilibrium constant of the reaction A₂(g) + B₂(g) → 2AB(g) is
A particular reaction has a negative value for the free energy change. Then at ordinary temperature
The difference between ΔH and ΔE for the combustion of methane at 27oC will be (in J mol-1)
CH4(g) + 2O2 → CO2(g) + 2H2O(l)
Δn = 1 - 3 = (-2)
∴ ΔH - ΔE = Δng RT = (-2) (8.314) (300)
A similarity between optical and geometrical isomerism is that
An electrochemical cell reaction is : Pt, H₂(1atm) ∣ HCl(0.1M)∣∣ CH₃COOH (0.1M)∣ H₂ (1atm), Pt. The e.m.f. of this cell will not be zero, because
In the electrochemical cell Pt, H2 (g) 1 atm ∕ H+ I M ∕ Cu2+ (1M) ∕ Cu(s). Which one of the following statements is true?
The ether that undergoes electrophilic substitution reactions is
Chromium is obtained by reducing purified chromite ore with
For an ideal gas, number of moles per litre in terms of its pressure P, gas contant R and temperature T is
The electronic configuration of an element is 1s₂2s₂2p₆3s₂3p₆3d₁₀4s₂4p₃. Its properties would be similar to which of the following elements?
Which of the following oxides of Nitrogen is anhydride of HNO3
In which of the following complexes, oxidation state of metal is zero ?
Which of the following describes the hexagonal close packed arrangement of spheres?
Which forms meso form on reaction with alkaline KMnO4?
Mercury is the only metal which is liquid at 0oC. This is due to its
The standard enthalpy of decomposition of N₂O₄ to NO₂ is 58.04 KJ and standard entropy of this reaction is 176.7 J-K-1. The standard free energy change for this reaction at 25oC, is
Fill in the blank with appropriate word.
Some regions of our country still remain........to the average man.
Out of the given alternatives, choose the one which can be substituted for the given capitalised word.
Many people CALLED ON the minister when he was ill.
Improve the sentence by choosing best alternative for capitalised part of the sentence.
He is not IN THE GOOD BOOKS of his master.