What will be the phase difference between virtual voltage and virtual current, when the current in the circuit is wattless
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The centre of mass of two particles with masses 4kg and 2kg located at (1,0,1), (2,2,0) respectively has the coordinates
A body of mass m is moving in a circle of radius r with a constant speed υ. The force on the body is mυ2/r and is directed towards the centre. What is the work done by this force in moving the body over half the circumference of the circle
The image of the sun is formed on the photosensitive metal with a convex lens and the photoelectric current is I . If the lens is replaced by another similar lens of half the diameter and double the focal length, then photoelectric current will be
A wheel having metal spokes of 1m long between its axle and rim is rotating in a magnetic field of flux density 5 x 10 − 5 T normal to the plane of the wheel. An e.m.f of 22/7 m V is produced between the rim and the axle of the wheel. The rate of rotation of the wheel in radians per second is
Two electric charge 12 μ C and − 6 μ C are places 20 cm apart in air. There will be a point P at which electric potential is zero on the line joining these two charges and outside, excluding the region between them. The distance of P from − 6 μ C charge is
There is a uniform electric field of strength 103 V m−1 along Y-axis. A body of mass 1 gm and charge 10 − 6 C is projected into the field from orgin along the positive X-axis with a velocity of 10 ms−1 . Its speed in ms−1 after 10s is (Neglect graviation )
The escape velocity of an object from the earth depends upon the mass of the earth (M), its mean density (ρ),its radius (R) and gravitational constant (G). Thus the formula for escape velocity is
The acceleration due to gravity at a height above the surface of the earth is 9ms−2 . Its value at a point at an equal distance below the surface of the earth is (take g = 10ms−2 on the surface)
The direction of magnetic line of force of a bar magnet is
24 cm3 of water flows per second through a capillary tube of radius r cm and length l cm, when connected to a pressure head h cm of water. If a tube of the length l/2 cm and radius r/2 cm is connected to the same pressure head, then volume of water flowing per second through the tube is
A wire of length L and area of cross-section A is made of material of Young's modulus y. If the wire is stretched by the amount x, the work done is
A cord is wound round the circumference of wheel of radius r. The axis of the wheel is horizontal and moment of inertia about it is I. A weight mg is attached to the end of the cord and falls from rest. After falling through a distance h, the angular velocity of the wheel will be
A man throws a ball vertically upward and it rises through 20 m and returns to his hands. What was the initial velocity (u) of the ball and how much time (t) it remained in the air? (g = 10 m/s2)
The angularspeed of seconds needle in a mechanical watch is
A body of mass m is moving in a circle of radius r with a constant speed υ. The force on the body is mυ2/r and is directed towards the centre. What is the work done by this force in moving the body over half the circumference of the circle
Three light strings are connected at the point P. A weight W is suspended from one of the strings .End A of string AP and end B of string PB are fixed as shown .In equilibrium PB is horizontal and PA makes an angle of 60o with the horizontal .If the tension in PB is 30 N then the tension in PA and weight W are respectively
A particle of mass m is projected with the velocity ν making an angle of 45o with the horizontal. The magnitude of the angular momentum of the particle about the point of projection when the particle is at its maximum height is (where g = acceleration due to gravity)