In an A.C. circuit containing an inductance only, the current
Photo electric emission is observed from a metallic surface for frequencies ν1 and ν2 of the incident light rays ν1 > ν2. If the maximum values of kinetic energy of the photo electrons emitted in the two cases are in the ration of 1 : K then the threshold frequency of the metallic surface is
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A wire of resistance R is cut into 'n' equal parts. These parts are then connected in parallel. The equivalent resistance of the combination will be
A steady current ι is flowing through a conductor of uniform cross-section. Any segment of the conductor has
The power factor of an a.c. circuit having resistance R and inductance L connected in series to an a.c. source of angular frequency ω is
Two condensers, one of capacity C and the other of capacity C/2 , are connected to a V volt battery, as shown.
The work done in charging fully both the condensers is
A transformer is used to reduce the mains supply of 220 V to 11 V. If the currents in primary and secondary coils are 5 A and 90 A respectively, efficiency of transformer is
A work of 100 J is done in moving a charge of -5C from infinity to a particular point in an electrostatic field. The potential of this point is
Three charges, each equal to +q, are placed at the corners of an equilateral triangle. If the force between any two charges is F, then net force on either charge will be
The coefficient of friction between a body and the surface of an inclined plane at 45º is 0.5. If g=9.8 m/s2, the acceleration of the body downwards in m/s2 is
A satellite revolves around the earth in an elliptical orbit. Its speed
Out of following, the only correct statement about satellites is
Newton's law of cooling, holds good only if the temperature difference between the body and the surroundings is
Two beams of light having intensities I and 4I interfere to produce a fringe pattern on a screen. The phase difference between the beams is π/2 at point A and π at point B. Then the differnce between the resultant intensities at A and B is
The average kinetic energy of a gas molecules at 27ºC is 6.3×10⁻²¹J. Its average kinetic energy at 227ºC will be
The magnetic field d̅B due to a small current element dl at a distance r and element carrying current i is
Magnetic field induction at one end on the axis of a long solenoid having n turns per unit lengh and carrying i ampere current is
A potential difference of 2V exists across a potentiometer wire of 2m length. When the potential difference across a 2Ω resistance of a second circuit is measured by this potentiometer wire, it amounts to 5mm balancing length. The current in the second circuit is
A bar magnet is oscillating in earth's magnetic field with a period T. What happens to its period of motion, if its mass is quadrupled ?
A body floats in a liquid contained in a beaker. If the whole system falls under gravity, then the upthrust on the body due to liquid is
A column of water 60 cm high supports a column of an unknown liquid of density 1500 kg-m⁻3. The height of liquid column is (Density of water = 1000 kg-m⁻3)
A cube is subjected to a uniform volumatric compression. If side of cube decreases by 1%, then its bulk strain is
Moment of inertia of a uniform circular disc about a diameter is I. Its moment of inertia about an axis perpendicular to its plane and passing through a point on its rim will be
The number of neutrons in a chain reaction increases in
What is the Q-value of the reaction
p + 7Li → 4He + 4He
The atomic masses of 1H , 4He and 7Li are 1.007825 u, 4.002603 u and 7.016004 u respectively