Electrons ejected from the surface of a metal, when light of cartain frequency is incident on it, are stopped fully by a retarding potential of 3 volts. Photo electric effect in this metallic surface begins at a frequency 6 x 1014 s-1 . The frequency of the incident light in s-1 is [ Planck′s constant = 6.4 x 10-34 J − sec ; charge on the electron = 1.6 x 10-19C ]
According to Einstein's Photo electric equation
hv = hv0 + K.E = hv0 + ev0
⇒ v0 = v0 + ev0 /h
⇒' v0 = 13.5 x1014 Js-1
In a transformer, the number of turns in primary coil and secondary coil are 5 and 4 respectively. If 240 V is applied on the primary coil, then the ratio of current in primary and secondary coil is
A 10 μ F capacitor and a 20 μ F capacitor are connected in series across 200 V supply line. The charged capacitors are then disconnected from the line and reconnected with their positive plates together and negative plates together and no external voltage is applied. What is the potential difference across each capacitor?
C1 = 10 μF , C2 = 20 μF
The velocity of helium nucleus travelling in curved path in a magnetic field is v. The velocity of proton moving in the same curved path, in the same magnetic field is
The quantity of electricity needed to liberate one gram equivalent of an element is
A laser beam is used for carrying out surgery because it
As the laser beam is highly monochromatic, directional and coherent, it can be sharply focussed.
Therefore it is used for carrying out surgery
A galvanometer of 25 Ω resistance can read a maximum current of 6mA. It can be used as a voltmeter to measure a maximum of 6 V by connecting a resistance to the galvanometer. Identify the correct choice in the given answers
An electrical cable having a resistance of 0.2 Ω delivers 10 kW at 200 V.D.C. to a factory. What is the efficiency of transmission?
A galvanometer of resistance of 98 Ω is shunted by a resistance of 2 Ω . The fraction of the total current that passes through the galvanometer 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 the first, then resistance of mercury column is
The curve drawn between velocity and frequency of photon in vacuum will be a
In a D.C. motor induced e.m.f will be maximum
The p.d. across an instrument in an A.C. circuit of frequency f is V and the current flowing through it is I such that V=5 cos 2 π ft amp. The power dissipated in the instrument is
Energy needed to establish an alternating current I in a coil of self inductance L is
E = 1/2 LI2
According to Maxwell's hypothesis, a changing electric field gives rise to
Eight dipoles of charges of magnitude e are placed inside a cube. The total electric flux coming out of the cube will be.
Potential energy of two equal positive charges 1 μ C each held 1 m apart in air is
An electron of charge e coulomb passes through a potential difference of V volt. Its energy in joule will be
If n capacitors each of capacitance C are connected in series with a battery of V volt, then electrostatic energy stored in all the capacitors will be
The equivalent capacitance Cs of these series-connected capacitors is
1/Cs = 1/C + 1/C + 1/C ..... n times = n C
∴ Cs = C/n
Energy stored in all capacitors = 1/2 CsV2 = 1/2 C/n V2 = 1/2n CV2
A doubly ionised He+2 atom travels at right angles to a magnetic field of induction 0.4T at a velocity of 105 m s-1 describing a circle of radius r. A proton travelling with same speed in the same direction in the same field will describe a circle of radius
Figure shows a solid hemisphere with a charge of 5nC distributed uniformly through its volume. The hemisphere lies on a plane and point P is located on the plane, along a radial line from the centre of curvature at distance 15cm. The electric potential at point P due to the hemisphere is:
A current carrying coil when freely suspended will allign itself
The material used to slow down neutrons in a reactor is called
Absorption of X-Rays is maximum in which of the following material sheet of same thickness?
The source of stellar energy is
The kinetic energy of photo-electrons depends upon the
The Figure shows a plot of photo current versus anode potential for a photo sensitive surface for three different radiations. Which one of the following is a correct statement?
The splitting of white into several colours on passing through a glass prism is due to
A ray is incident on an equilateral prism of μ = 2 such that ray inside the prism goes parallel to the base. Find angle of minimum deviation?
Which of the following is not a transducer?
In an insulator the energy gap between conduction and the valence band is about
A rectifier converts
At room temperature, a P-type semiconductor has
When a P-N junction diode is forward biased potential barrier
In a common base amplifier circuit, calculate the change in base current if that in the emitter current is 2 mA and α = 0.98
The dominant mechanism for motion of charge carriers in forward and reverse biased silicon p-n junction are
In Young's experiment of double slit, the intensity of central bright band is ---- times the individual intensities of the interfering waves
In soap bubble, colouration is obtained when illuminated by white light due to
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
A wave front travels
Ethyl alcohol is industrially prepared from ethylene by
The product formed by the reaction of chlorine with benzaldehyde in the absence of a catalyst is
The product acetal is produced by reacting alcohol in the presence of dry HCl with
Schiff's reagent is
Pure methane can be produced by
Ozonolysis of C₇H₁₄ gave 2-methyl-3-pentanone toluene. The alkene is
The unit for electric current is
Heterolytic cleavage of a covalent bond gives only
Ascorbic acid is a chemical name of
Amino acids are produced on hydrolysis of
Carbohydrates are used by body mainly
What will happen if LiAlH₄ is added to an ester ?
Ethyl isocyanide on acidic hydrolysis generates
Carboxylic acids are more acidic than phenol and alcohol because of
Two moles of HI was heated in a sealed tube at 440oC till the equilibrium was reached. HI was found to be 22% decomposed. The equilibrium constant for dissociation is
At certain temperature, 50% of HI is dissociated into H2 and I2, the equilibrium constant is
For a system in equilibrium, ∆G=0, under conditions of constant
If an endothermic reaction is non-spontaneous at freezing point of water and becomes feasible at its boiling point, then
What is the entropy change (in J K-1 mol-1), when one mole of ice is converted into water at 0oC? (The enthalpy change for the conversion of ice to liquid water is 6.0kJ mol-1 at 0oC)
The commonly used antiseptic in cosmetics is
Which of the following has sp2 hybridisation ?
The co-ordination no. and oxidation no. of Cr in K₃[Cr(C₂O₄)₃] are respectively
The reaction takes place with
Hydrolysis of benzonitrile gives
Which of the following reagent can be used to convert benzene diazonium chloride into benzene ?
At cathode ,the electrolysis of aqueous Na₂SO₄ gives
Standard electrode potential of three metals A,B and C are + 0.5 V, -3.0 and -1.2 V respectively. The reducing power of these metals are
Ethyl chloride is converted into diethyl ether by
Which of the following imparts violet colouration to the non-luminous flame of Bunsen burner?
A sample of gas has a volume of 0.2 lit measured at 1 atm pressure and 0oC. At the same pressure, but at 273oC its volume will become
An alloy which does not contain copper is
PH₃, the hydride of phosphorus is
Which of the following is an acid ?
Consider the reaction, Zn + Cu2+ → Zn2+ + Cu. With reference to the above, which one of the following is the correct statement?
Following eclipsed form of propane is repeated after rotation of:
A colloidal solution of a liquid, in a solid, is termed as
Which of the following is ferroelectric compound ?
The transition metals have a less tendency to form ions due to
Reaction of zinc with cold and very dil. HNO₃ gives
Find the Antonym of LEAP
Find the Synonym of EXPLICIT
Fill in the blank with appropriate word.
The country needs a.......government to tackle the challenges it faces today.
Out of the given alternatives, choose the one which can be substituted for the given capitalised word.
The rebels HELD OUT for about a month.
Improve the sentence by choosing best alternative for capitalised part of the sentence.
Not till he got home HE DID REALISE that he had lost his keys in the theatre.