A transformer connected to 220 volt line shows an output of 2 A at 11000 volt. The efficiency is 100%. The current drawn from the line is
Radioactive nuclei that are injected into a patient, collect at certain sites within the body, undergoing radioactive decay and emitting electromagnetic radiation. These radiations are recorded by a detector. This procedure provides diagnostic tool called
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An L.C. circuit contains 10 mH inductor and a 25 μ F capacitor. The resistance of the circuit is negligible. The energy stored in the circuit is completely magnetic at time (in milli seconds) being measured from the instant when the circuit is closed
The angular speed of a fly wheel making 120 revolutions/minute is
The electric resistance of a certain wire of iron is R. If its length and radius are both doubled, then its
The coefficient of restitution e for a perfectly inelastic collision is
Energies of electrons can be increased by allowing them
A pan with set of weights is attached with a light spring. When disturbed, the mass-spring system oscillates with a time period of 0.6 s. When some additional weights are added then time period is 0.7s. The extension caused by the additional weights is approximately given by
If the output of a logic gate is 0 when all its inputs are at logic 1, then the gate is either:
A body is sliding down an inclined plane having coefficient of friction 0.5. If the normal reaction is twice that of the resultant downward force along the incline,the angle between the inclined plane and the horizontal is
Capacitance of a capacitor becomes 7/6 times its original value if a dielectric slab of thickness, t = 2/3 d is introduced in between the plates. 'd' is the separation between the plates. The dielectric constant of the dielectric slab is
The value of g on moon diameter is 1/4 th that of the earth and whose mass is 1/6 th that of the earth. The ratio of escape velocities at moon's and earth's surface is nearly
According to the experiment of Ingen Hausz the relation between the thermal conductivity of a metal rod is K and the length of the rod whenever the wax melts is
At the same temperature, the mean kinetic energies of molecules of hydrogen and oxygen are in the ratio
A 20 kg block is initially at rest. A 75 force is required to set the block in motion. After the motion, a force of 60 N is applied to keep the block moving with constant speed. The coefficient of static friction is
A microammeter has a resistance of 100 Ω and full scale range of 50 μ A. It can be used as a voltmeter or as a higher range ammeter provided a resistance is added to it. Pick the correct range and resistance combination
At the magnetic poles of the earth, a compass needle will be
Two liquids of densities ρ₁ and ρ₂ and coefficients of viscosity η₁ and η₂ are found to flow through a capillary tube at the same rate. The ratio of η₁/η₂ is
A train starts from rest with an acceleration a and describes distances s₁, s₂ and s₃ in the first, second and third seconds of its journey. The ratio of s₁ : s₂ : s₃ is
A weightless thread can bear tension upto 3.7 kg wt. A stone of mass 500 gms is tied to it and revolved in a circular path of radius 4 m in a vertical plane. If g = 10 ms-2, then the maximum angular velocity of the stone will be
The ratio of the weight of a man in a stationary lift and when it is moving downward with uniform acceleration 'a' is 3:2. The value of 'a' is (g-Acceleration due to gravity of the earth)
A mass m is vertically suspended from a spring of negligible mass. The system oscillates with a frequency n. What will be the frequency of the system, if a mass 4m is suspended from the same spring ?
When a body is thrown with a velocity u making an angle θ with the horizontal plane, the maximum distance covered by it in horizontal direction is
An air bubble is released from the bottom of a pond and is found to expand to thrice its original volume as it reaches the surface. If the atmospheric pressure is 100 k Pa, the absolute pressure at the bottom of lake in k Pa is... (assume no temperature variation)
Water rises in a capillary tube when its one end is dipped vertically in it, is 3 cm. If the surface tension of water is 75x10-3 N/m, then the diameter of capillary will be
An electric bulb marked 40 W and 200 V, is used in a circuit of supply voltage 100 V. Now its power is
A homogeneous disc of mass 2 kg and radius 15 cm is rotating about its axis (which is fixed) with an angular velocity of 4 radian/s. The linear momentum of the disc is
A lead ball moving with a velocity V strikes a wall and stops. If 50% of its energy is converted into heat, then what will be the increase in temprature (Specific heat of lead is S)
The coefficient of linear expansion of brass and steel are α 1 and α 2 . If we take a brass rod of length l1 and steel rod of length l2 at 0oC, their difference in length (l2 - l1) will remain the same at all temperatures if
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1 videos|1 docs|68 tests
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