An oscillator circuit consists of an inductance of 0.5 mH and a capacitor of 20μF. The resonant frequency of the circuit is nearly
The penetrating power of X - rays increases with the
An electron and a proton have the same wave length. Which one of the following statements is correct about them?
A 10 μ F capacitor is charged to a potential difference of 50 V and is connected to another uncharged capacitor in parallel. Now the common potential difference 20 volt. The capacitance of second capacitor is
The resistance of a cell does not depend upon
If sky wave with a frequency of 50 MHz is incident on D-region at an angle of 30o, then angle of refraction is
For a metallic wire, the ratio V/i (V= the applied potential difference, i= current flowing) is
The resistance of a wire is 10Ω. Its length is increased by 10% by stretching. The new resistance will now be
A moving coil galvanometer is converted into an ammeter reading upto 0.03 A by connecting a shunt of resistance 4r across it and into an ammeter reading upto 0.06 A when a shunt of resistance r is connected across it. What is the maximum current which can be sent through this galvanometer if no shunt is used
An electrical meter of internal resistance 20 Ω gives a full scale deflection when one milliampere current flows through it. The maximum current, that can be measured by using three resistors of resistance 12 Ω each, in milliamperes is
If an electron of mass m and charge e is accelerated from rest through a potential difference V in vacuum, then its final velocity will be
If the rotational velocity of a dynamo armature is doubled, then induced emf will
The primary and secondary coils of a transformer have 50 and 1500 turns respectively. If the magnetic flux φ linked with the primary coil is given by φ = φ 0 + 4t, where φ is in weber, t is time in second and φ 0 is a constant, the output voltage across the secondary coil is
No. of turns across primary Np = 50
Number of turns across secondary Ns = 1500
Magnetic flux linked with primary, Φ = Φ0 + 4t
∴ Voltage across the primary,
Two coils have self inductance L1 = 4 m H and L2 = 1 m H respectively. The currents in the two coils are increased at the same rate. At a certain instant of time both coils are given the same power. If i1 and i2 are the currents in the two coils, as that instant of time respectively, then the value of i1/ i2 is
Which of the following is/are not electromagnetic waves?
Two equal charges, q each are placed at a distance of 2a, and a third charge -2q is placed at the mid point. The potential energy of the system is
A charge q is placed at the corner of a cube of side l. The electric flux passing through the cube is
Eight cubes, each side l, are required to form a Gaussian surface
So that the charge q at the corner of a small cube appears at the centre of the bigger cube
According to Gauss's law, the electric flux through the bigger cubes = q/∈0
Hence the electric flux through the given small cube = q/8∈0
Two equal charges q of opposite sign separated by a distance 2a constitute an electric dipole of dipole moment p. If P is a point at a distance r from the centre of the dipole and the line joining centre to this point makes an angle θ with the axis of the dipole, then potential at the point P is given by
The plates of a parallel plate capacitor are charged upto 200 volts. A dielectric slab of thickness 4 mm is inserted between its plates. Then to maintain the same potential difference between the plates capacitor, the distance between the plates is increased by 3.2 mm. The dielectric constant of dielectric slab is
Eight dipoles of charges of magnitude q are placed inside a cube. The total electric flux coming out of the cube will be
Five equal capacitors connected in series have a resultant capacitance of 4 μ F. The total energy stored in these, when these are connected in parallel and charged to 400V is
A long solenoid carrying a current produces a magnetic field B along its axis. if the current is doubled and the number of turns per cm is halved, the new value of magnetic field is
Neutron was discovered by
When the nucleus of a radioactive element emits an alpha particle, the atomic number is decreases by
The material used to slow down neutrons in a reactor is called
A photo cell is receiving light from a source placed at a distance of 1 m. If the same source is to be placed at a distance of 2m, then the ejected electron
The work function of a metal is 2.8 eV. Its threshold wavelength will be
A ray of light is incident on a plane mirror at an angle of 60o . The angle of deviation produced by the mirror is
A concave mirror gives an image three times as large as the object placed at a distance of 20 cm from it. For the image to be real, the focal length should be
m = -3, m = - v u
-3 = - v -20
⇒ v = - 60 cm
Now, u = - 20, v = - 60, f = ?
A semiconductor device which is used for detecting light intensity is called a
A p-n photodiode is fabricated from a semiconductor with band gap of 2.8 eV. Which of the following wavelengths it can detect?
Which is true about the following? I An amplifier is necessarily an oscillator too II An oscillator is necessarily an amplifier too
A semiconductor device is connected in a series circuit with a battery and a resistance. A current is found to pass through the circuit. If the polarity of the battery is reversed, the current drops almost to zero. The device may be
The reverse biasing in a p-n junction diode
The dominant mechanism for motion of charge carriers in forward and reverse biased silicon p-n junction are
In a P-type semiconductor
In young's double slit experiment, the intensity of central maximum is I. It one slit is closed, the intensity at the same place will become
When distance between source of light and observer decreases, then the apparent frequency of light
Two identical light waves, propagating in the same direction, have a phase difference δ . After they superpose the intensity of the resulting wave will be proportional to
In Young's double slit experiment, the width of the fringes obtained with light of wavelength 6000 Angstrom is 2.0mm. The fringe width, if the entire apparatus is immersed in a liquid of refractive index 1.33, will be
Fringe width in Young's double slit experiment β = Dλ/d
When apparatus is immersed in liquid, only wavelength of light (λ) changes
Wavelength of light is liquid,
λ' = λ/n , where n = refractive index of medium
Initial fringe width, β = Dλ/d .....(i)
Fringe width in liquid, β' = Dλ' /d .....(ii)
Dividing Equation (ii) by Equation (i), we get
C₆H₅CHO + HCN → C₆H₅CH(CN)OH. The product would be
The boiling point of glycerol is more than propanol because of
Which does not react with Fehling solution ?
Propanone is methyl ketone
So ketones do not react with fehling's solution
Which of the following reagent react differently with HCHO and CH₃CHO and CH₃COCH₃
The reaction/method that does not give an alkane is
1, 3-Butadiene when treated with Br₂ gives
The units nanometer, fermi, angstrom and attometre arranged in decreasing order
The least count of an instrument is 0.01cm. Taking all precautions, the most possible error in the measurement can be
Carboxylic acids are more acidic than phenol and alcohol because of
Which of the following is a disaccharide?
Calorific value is in order
The metal present in vitamin B₁₂ is
The acid amide is converted into acid with evolution of nitrogen gas by
Which of the following salt can be produced by the reaction of CO and caustic soda ?
The rate, at which a substance reacts at constant temperature, depends upon its
In a closed insulated container, a liquid is stirred with a paddle to increase its temperature. In this process, which of the following is true?
When H₂ and I₂ are mixed and equilibrium is attained, then
If a gas at constant temperature and pressure expands, then its
Which of the following is not correct?
A drug that is antipyretic as well as analgesic is
The systematic name of (CH₃)₂CH-COOH is
The number of possible isomers of an octahedral complex, [ Co(C2O4)2(NH3)2 ] − is :
The organometallic compound which is used as a catalyst in the hydrogenation of alkenes or alkynes is
Hydrolysis of benzonitrile gives
Hinsberg reagent is
The reagent used for the preparation of higher ethers from hologenated ethers is
During smelting an additional substance is added which combines with impurities to form a fusible product. It is known as
Which of the following is not a reducing agent ?
Oxidation no. of chlorine in hypochlorous acid is
Consider the following four electrodes
A = Cu+2 0.0001 M | Cu (s)
B = Cu+2 0.1 M | Cu (s)
C = Cu+2 0.01 M |Cu (s)
D = Cu+2 0.001 M | Cu (s)
If the standard reduction potential of Cu+2 ∕ Cu is + 0.34 V , the reduction potential (in volts) of the above electrodes follow the order
Sodium hexametaphosphate is known as
C and Si have
0.24 g of a volatile gas upon vapourisation gives 45 ml vapour of N.T.P. what will be vapour density of the substance ? (Density of H₂ = 0.089 gl-1)
Basicity of orthophosphoric acid is
To get n-type doped semiconductor, impurity to be added to silicon should have the following number of valence electrons
Which of the following has the same oxidation state as that of Cr in K₂CrO₃
Following eclipsed form of propane is repeated after rotation of:
Medicines are more effective, if they are used in
The white anhydrous copper sulphate decomposes to give
Which of the following is ionic in nature ?
Fill in the blank with appropriate word.
No matter what.......come our way, we should not lose our temper.
Find the Antonym of HINDRANCE
Find the synonym of AMITY
Choose the alternative which best expresses the meaning of the idiom/phrase.
Feathering one's nest
Improve the sentence by choosing best alternative for capitalised part of the sentence.
When the train finally CAME INTO the station the lonely traveller seemed relieved.