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An electron beam is subjected to perpendicular electric and magnetic fields of 5x10-4 wbm-2 and 3x103 Vm-1 resectively. If there is no deflection, the velocity of electrons is
In an induction coil with resistance, the induced emf will be maximum when
The energy of an X - ray photon of wavelength 1.65 Å is (h = 6.6x10-4 J - s ; c = 3x108 m s-1 ; 1 e V = 1.6 x 10-19 J
A sheet of aluminium foil of negligible thickness is introduced between the plates of a capacitor. The capacitance of the capacitor
The thickness of the foil is negligible
Of the following, the one that does not make use of chemical effect of electric current is
Consider telecommunication through optical fibres. Which of the following statements is not correct
When connected across the terminals of a cell, a voltmeter measures 5V and a connected ammeter measures 10 A of current. A resistance of 2 ohms is connected across the terminals of the cell. The current flowing through this resistance will be
The balancing length for a cell is 560cm in a potentiometer experiment when an extenral resistance of 10 Ω is connected in parallel to the cell, the balancing length changes by 60cm. The internal resistance of the cell in ohms is
If only 2% of the main current is to be pass through a galvanometer of resistance G, then the resistance of shunt will be
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 the first, then resistance of mercury column is
A rectangular coil of 300 turns has an area of 25 cm.x10cm. The coil rotates with a speed of 50 cps in a uniform magentic field of 4x10-2 T, about an axis perpendicular to the field. The peak value of the induced e.m.f. is
Induced emf in a rectangular coil is given by : E = nBAωsin θ
substituting n = 300; B = 4 x 10-2 − T ;
A = 25 x 10 x 10-4 m2
ω = 2 π v = 2 x 50 π rad s − 1
θ = 90 ∘ ,
we get; E = 30Πv
Which of the following does not obey the phenomenon of mutual induction?
A cylinder of radius R and length L is placed in a uniform electric field E parallel to the cylinder axis, the total electric flux for the surface of the cylinder is
Total charge enclosed is zero
If a point charge q be rotated in a circle of radius r around a charge Q, the work done will be
Potential energy of two equal positive charges 1 μ C each held 1 m apart in air is
A capacitor of capacity 10 μ F is charged to 40V and a second capacitor of capacity 15 μ F is charged to 30V. If they are connected in parallel the amount of charge that flows from the smaller capacitor to higher capacitor in μ C is
Amount of charge flowing = 10 x 40 − 10 x 34 = 60
An infinite number of charge of equal magnitude q, but of opposite sign are placed along the X-axis at x = 1, x = 2, x = 4, x = 8... and so on. The electric potential at the point x = 0 due to these charge will be
A wire of length L metre, carrying a current I ampere is bent in the form of a circle. its magnitude of magnetic moment will be
Neutrino emission in β decay was predicted theoretically by
Which one of the following is true in photoelectric emission
An image of the sun is formed by a lens of focal length 30 cm on the metal surface of a photoelectric cell and a photoelectric current (I) is produced. The lens forming the image is then replaced by another of the same diameter but of focal length of 15 cm. The photelectric current in this case is
A ray of light is incident on a surface of glass slab at an angle 450 . If the lateral shift produced per unit thickness is 1/√3 m, the angle of refraction produced is
A light incident at 600 on one of the faces of a 300 prism experiences a deviation of 300 . The angle made by the light beam with the second face is
The voltage gain of an amplifier with 9% negative feedback is 10. The voltage gain without feedback will be
The width of forbidden gap in silicon crystal is 1.1 eV. When the crystal is converted into a n - type semiconductor, the distance of fermi level from conduction band is
When the electrical conductivity of a semiconductor is due to the breaking of its covalent bonds, then the semiconductor is said to be
On increasing the reverse bias to a large value in a P-N junction diode current
Two sources of same intensity interfere at a point and produced resultant I. When one source is removed, the intensity at that point will be
If the two slits in Young's experiment have width ratio 1:4, the ratio of intensity at maxima and minima in the interference pattern in
For which property are electrons used in an electron microscope?
In Young's double slit experiment, two slits are made 5 mm apart and the screen is placed 2 m away. What is the fringe separation when light of wavelength 500 nm is used?
Zerewitnoff's determination of active hydrogen in a compound is based upon its reaction with
The general order of reactivity of carbonyl compounds towards nucleophilic addition reactions is?
A compound A has molecular formula C₂Cl₃OH. It reduce Fehling's solution and on oxidation gives a monocarboxylic acid B. A is obtained by the action of Cl₂ on ethyl alcohol. A is
The reaction CH₃CH₂Br + OH- → CH₃CH₂OH + Br- is an example of;
The conversion of Cl ― CH ═ CH ― Cl to Cl₂CH ― CHCl₂ can be carried out with
The bond that determines the secondary structure of a protein is
Saponification of ethyl benzoate with caustic soada as alkali,gives
Hydrolysis of an ester gives a carboxylic acid which on Kolbe's electrolysis yields ethane. The ester is
The equilibrium constant in a reversible chemical reaction at a given temperature
The heat of combustion of methane at 298K is expressed by
CH4 g + 2O2 g → CO2 g + 2 H2O l , Δ H = − 890.2 k J . The magnitude of Δ E of the reaction at this temperature is
In the reaction CH2COOHaq + OH(aq) → CH3COO- + H2O(l) ; ΔH = -55.2kJ mol-1 What is the heat of dissociation (in kJ mol-1) of acetic acid?
ΔH = -55.2 KJ.mol-1
-[H+ (aq) + OH- (aq) → H2O(l) ΔH = -57.3 KJ .mol-1]]
CH2COOHaq → CH3COO- (aq) + H+ (aq) ΔH = ?
CH2COOH(aq) + OH- (aq) → CH3COO- (aq) + H2O(l) ΔH = -55.2 KJ .mol-1
-H+ + OH- (aq) → - H2O(l) ΔH = + 57.3KJ .mol-1
CH3COOH(aq) → CH3COO- (aq) + H+(aq) ΔH = 2.1 KJmol-1
Consider the following reaction
C + O2 → CO2 , Δ H = − 400 k J ∕ mole
2H2 + O2 → 2 H2O , Δ H = − 570 k J ∕ m o l e ;
CO2 + 2 H2O → CH4 + 2O2 , Δ H = 800 k J ∕ m o e
The heat of formation of methane is
In the diazotisation of aniline with sodium nitrite and hydrochloric acid, the excess of hydrochloric acid is used primarily to
Among TiF₆2-,Co₆3-,Cu₂Cl₂ and Ni₄4-(at.nos.:Ti=22, Co=27, Cu=29, Ni=28). The colourless species are
The number of unpaired electrons calculated in [ Co(NH3)6]3+ and [ CoF6 ]3- are
Reduction of H₃C ― NC with hydrogen in the presence of Ni/Pt catalyst gives
The e.m.f. of a galvanic cell with electrode potentials of silver equal to + 0.80 V and that of copper equal to + 0.34 V is
The pH of aqueous KCl solution is 7.0. This solution was electrolysed for a few seconds using Pt electrodes. Which of the following is correct?
The standard emf of the cell Zn + Cu2+ → Cu + Zn2 is 1.10 V at 250C. The emf of the cell when 0.1 M Cu2+ and 0.1 M Zn2+ solutions are used will be
If the weight of 5.6 liters of a gas at N.T.P. is 11 gram. The gas may be
In the manufacture of cement which of the following is used?
Which of the following is the best source of thallium?
White phosphorus when boiled with strong solution of caustic soda produces :
Which of the following contains maximum number of unpaired electrons?
Fill in the blank with appropriate word.
The passengers and crew members of the aeroplane had a.......escape when it was taking off from the runway.
Out of the given alternatives, choose the one which can be substituted for the given capitalised word.
There is NO LOVE LOST between the two neighbours.
Improve the sentence by choosing best alternative for capitalised part of the sentence.
When the solider returned home after the war was over, his wife received him WITH OPEN HANDS.