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The value of current, flowing through an inductor of inductance 1 H and having negligible resistance when connected to an a.c. source of 200 V and 50 Hz, is
The negative Zn pole of Daniell cell, sending a constant current through a circuit, decreases in mass by 0.13g in 30 min. If the electrochemical equivalent of Zn and Cu are 32.5 and 31.5 respectively, the increase in the mass of the positive Cu pole in this time is
Two ions having masses in the ratio 1 : 1 and charges 1 : 2 are projected into uniform magnetic field perpendicular to the field with speeds in the ratio 2 : 3. The ratio of the radii of circular paths along which the two particles move is
Two identical cells each of emf E and internal resistance r are connected in parallel with an external resistance R. To get maximum power developed across R, the value of R is
According to max. power transfer theorem, power transferred to the load will be maximum when load resistance is equal to internal resistance
i.e., R = r/2
In a potentiometer, the null point is received at 7th wire. If now we have to change the null point at 9th wire, what should we do?
If two identical heaters of 220 V, 1000 W are placed parallel to each other across 220 V lines, then the combined power of the heaters is
A wheel having metal spokes of 1m long between its axle and rim is rotating in a magnetic field of flux density 5x10^{5} T normal to the plane of the wheel. An e.m.f of 22/7 mV is produced between the rim and the axle of the wheel. The rate of rotation of the wheel in radians per second is
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 N_{p} = 50
Number of turns across secondary N_{s} = 1500
Magnetic flux linked with primary, Φ = Φ_{0} + 4t
∴ Voltage across the primary,
Eight dipoles of charges of magnitude e are placed inside a cube. The total electric flux coming out of the cube will be
A hollow metal sphere of radious 10 cm is charged such that the potential on its surface is 80V. The potential at the centre of the sphere is
In bringing an electron towards another electron, the electrostatic potential energy of the system
The capacitance of a parallel plate capacitor is 10 μF when distance between its plates is 8 cm. If distance between the plates is reduced to 4 cm, its capacitance will be
A solid conducting sphere having a charge Q is surrounded by an uncharged concentric conducting hollow spherical shell. The potential difference between the surfaces of solid sphere and hollow shell is V. If the shell is now given a charge of 3Q, then the new potential difference between the two surfaces will be
In radioactive decay process, the negatively charged emitted β particles are
A straight wire of length 0.5 meter and carrying a current of 1.2 ampere is placed in a uniform magnetic field of induction 2 telsa. The magnetic field is perpendicular to the length of the wire. The force on the wire is
A thin spherical conducting shell of radius R has charge q. Another charge Q is placed at the centre of the shell. The electrostatic potential at a point P at a distance R/2 from the centre of the shell is
The masses of neutron, proton and deuteron in a.m.u are 1.00893 1.00813 and 2.01473 respectively. The packing fraction of the deuteron in a.m.u is
Packing fraction = (M  A)/A , where M is the atomic mass and A is the mass number.
The energy released per fission of a U^{235} nucleus is around
A photon of energy 3.4 eV is incident on a metal having work function 2 eV. The maximum K.E. of photoelectrons is equal to
The photoelectric work function for a metal surface is 4.125 eV. The cut off wavelength for this surface is
Work function W_{0} = hc/λ
The refractive index of glass is 1.520 for red light and 1.525 for blue light. Let D_{1} and D_{2} be angels of minimum deviation for red and blue light respectively in a prism of this glass, then,
In visible region the dispersive powers and the mean angular deviations for crown and flint glass prisms are ω , ω ' and d, d' respectively. The condition for getting dispersion with zero deviation, when the two prisms are combined is
Ntype semiconductors will be obtained, when germanium is doped with
When the P end of PN junction is connected to the negative terminal of the battery and the N end to the positive terminal of the battery, then the PN junction behaves like
The valency of an impurity added to germanium crystal in order to convert it into a Ptype semiconductor is
Laser light is considered to be coherent as it consists of
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
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
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