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In a circuit, L, C and R are connected in series with an alternating voltage source of frequency f. The current leads the voltage by 45^{o}. The value of C is
A hotwire ammeter reads 10 A in a a.c. circuit. The peak value of the current is
Hot wire ammeter always gives rms value of current, i.e.,
I_{rms} = 10 amp. as I_{rms} = I_{0}/√2
hence I_{0 }= √2 I_{rms} = √2 x 10 amp = 10√2 A
The average acceleration vector for a particle having a uniform circular motion is
A dipole of dipole moment p̅ is placed in uniform electric field E̅, then torque acting on it is given by
The gyromagnetic ratio of an electron of charge e and mass m is equal to
An electric dipole is placed along the Xaxis at the origin O. A point P is at a distance of 20 cm from this origin such that OP makes an angle π/3 with the X axis. If electric field at P makes an angle θ with Xaxis, the value of θ is
In the following combinations of logic gates, the outputs of A, B and C are respectivley
An alpha nucleus of energy 1/2 mv^{2} bombards a heavy nuclear target of charge Ze. Then the distance of closest approach for the alpha nucleus will be proportional to
A disc is of mass M and radius r. The moment of inertia of it about an axis tangential to its edge and in plane of the disc or parallel to its diameter is
Helium gas at 27^{o}C has a volume of 8 L. It is suddenly compressed to a volume of 1 L. The final temperature of the gas will be(γ = 5/3 )
T_{1} V_{1} ^{γ1} = T_{2} V_{2} ^{γ1}
or 300 (8)^{5/3  1} = T_{2} (1)^{5/3  1}
T_{2} = 300 {(2)^{3}}^{2/3} = 1200 K
or T_{2} = 927^{o}C
The radionuclide ^{56}Mn is being produced in a cyclotron at a constant rate P by bombarding a manganese target with deutrons. ^{56}Mn has a half life of 2.5 hours and the target contains large number of only the stable manganese isotope ^{55}Mn. The reaction that produces ^{56}Mn is:
^{55}Mn + d →^{56}Mn+P
After being bombarded for a long time, the activity of ^{56}Mn becomes constant equal to 13.86×10^{10}s^{−1}. (Use ln2 = 0.693; Avogadro number = 6×10^{23}; atomic weight of ^{56}Mn = 56gm/mole)
Q. After a long time bombardment, number of ^{56}Mn nuclei present in the target depends upon
(a) The number of ^{56}Mn nuclei present at the start of the process
(b) Half life of the ^{56}Mn
(c) The constant rate of production P
After five halflives percentage of original radioactive atoms left is:
In series LR circuit X_{L} = 3R. Now a capacitor with X_{C} = R is added in series. Ratio of new to old power factor is :
In a galvanometer, the deflection becomes one half when the galvanometer is shunted by a 20Ω resistor. The galvanometer resistance is
If an objects is placed symmetrically between two plane mirrors, inclined at an angle of 72°, then the total number of images formed is :
A tuning fork gives 4 beats with 50cm length of a sonometer wire. If the length of the wire is shortened by 1cm, the number of beats is still the same. The frequency of the fork (in Hz) is :
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