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A current flows in an a.c. circuit. An e.m.f. E − E_{0} sin ω t is applied to it. Then the power consumption P is
Two wires of the same dimensions but resistivities ρ₁ and ρ₂ are connected in series. The equivalent resistivity of the combination is
A potential difference of V is applied at the ends of a copper wire of length l and diameter d. On doubling only d, drift velocity
If intensity of incident light is increased in PEE then which of the following is true
The de Broglie wavelength associated with the particle of mass m moving with velocity v is
The current flowing in a coil of self inductance 0.4 mH is increased by 250 mA in 0.1 s. The e.m.f. induced will be
As current is increasing, induced e.m.f. is in opposite direction, therefore, e =  1 mV.
A capacitor of capacitance 1 μ F is charged to 1KV. The energy stored in the capacitor in joules is
C = 1μF
V = 1KV
energy stored U = 1/2 (CV^{2})
= 1/2 * 1 * 1^{2} = 0.5
When we touch the terminals of a high voltage capacitor, even after a high voltage has been cut off, then the capacitor has a tendency to
It is easier to roll a barrel than pull it along the road. This statement is
If radius of the earth contracted 2% and its mass remains the same then weight of the body at the earth surface
A black body radiates 20J of energy at 227^{o}C temperature.If temperature of the black body is changed to 727^{o}C, then energy radiated will be
A gas at certain temperature and volume has a pressure equal to 75 cm of Hg. If the mass of the gas is doubled, at the same volume and same temperature, its new pressure will be
The magnetic field at the centre of a circular coil of radius r carrying current I is B₁. The field at the centre of another coil of radius 2 r carrying same current I is B₂. The ratio B₁/B₂ is
When a diamagnetic substance is brought near north or south pole of a bar magnet is
Spherical balls of radius R are falling in a viscous fluid of viscosity η with a velocity v. The retarding viscous force acting on the spherical ball is
A wire of length L and radius a rigidly fixed at one end. On stretching the other end of the wire with a force F, the increase in it length is l. If another wire of same material but of length 2L and radius 2a is stretched with a force 2F, the increase in its length will be
Water drops fall at regular intervals from a tap which is 5 m above the ground. The third drop is leaving the tap at the instant the first drop touches the ground. How far above the ground is the second drop at that instant
A circular road of radius 1000 m has banking angle 45^{o}. The maximum safe speed of a car having mass 2000 kg will be, if the coefficient of friction between tyre and road is 0.5
The distance travelled by an object along the axes are given by x = 2t^{2}, y = t^{2}  4t, z = 3t  5. The initial velocity of the particle is
A body of mass 2 kg is hung on a spring balance mounted vertically in a lift. If the lift descends with an acceleration equal to the acceleration due to gravity 'g', the reading on the spring balance will be
A body is executing simple harmonic motion with an angular frequency 2 rad/s. The velocity of the body at 20 mm displacement, when the amplitude of motion is 60 mm, is
If a spring extends by x on loading, then the energy stored by the spring is (if T is tension in the spring and k is spring constant)
Two plane mirrors are inclined at an angle θ . It is found that a ray incident on one mirror at any angles is rendered parallel to itself after reflection from both the mirrors. The value of θ is
Of two eggs which have identical sizes, shapes and weights, one is raw and the other is halfboiled. The ratio between the moment of inertia of the raw egg and that of the halfboiled egg about a central axis is
A ring of radius r and mass m rotates about an axis passing through its centre and perpendicular to its plane with angular velocity ω. Its kinetic energy is
Two electric bulbs (60 W and 100 W respectively) are connected in series. The current passing through them is
A mass of liquid with volume V₁ is completely changed into a gas of volume V₂ at a constant external pressure P and temprature T. If the latent heat of evaporation for the given mass is L, then the increase in the internal energy of the system is
When the heat energy is supplied to the liquid, it is absorbed by the liquid and a phase change occurs from liquid state to gaseous state. The amount of heat absorbed by the liquid molecules is transferred to the vapor molecules.
Thus latent heat 'L' is given by,
L=Q/m
where Q is the amount of heat energy supplied to the liquid and m is mass of the liquid.
For a unit mass of liquid,
L=Q
The latent heat of vaporization is the amount of heat energy supplied by heating, according to first law of thermodynamics,
L=δE+PδV
δE=L−PδV
δE=L−P(V2−V1)
where,
δE is change in internal energy of the gas,
P is atmospheric pressure,
δV is change in volume
V1 is the volume of liquid and
V2 is the volume of gas
When the amount of work done is 300 J and change in internal energy is 100 J, then the heat energy supplied is
When distance between source of light and observer decreases, then the apparent frequency of light
Transverse waves of same frequency are generated in two steel wires A and B. The diameter of A is twice of B and the tension in A is half that in B. The ratio of velocities of wave in A and B is
When the waves y₁ = a sin ωt and y₂ = a cos ωt are superimposed, then resultant amplitude is
A body of mass 6 kg is under a force which causes displacement in it given by S = t^{2}/4 metres where t is time. The work done by the force in 2 seconds is
The physical quantity which has the dimensional formula M^{1}T^{⁻3} is
A long spring when stretched by x cm has a potential energy V. On increasing the stretching to nx cm, the potential energy stored in the spring is
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
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