100 g of water is heated from 30°C to 50°C. Ignoring the slight expansion of the water, the change in its internal energy is (specific heat of water is 4184 J kg ^{-1}K^{-1})
A screw gauge gives the following reading when used to measure the diameter of a wire.
Main scale reading : 0 mm
Circular scale reading : 52 divisions
Given that 1 mm on main scale corresponds to 100 divisions of the circular scale.
The diameter of wire from the above data is :
0.52 cm
0.052 cm
0.026 cm
0.005 cm
A current flows in an infinitely long wire with cross-section in the form of a semicircular ring of radius The magnitude of the magnetic induction along its axis is
The electrostatic potential inside a charged spherical ball is given by where is the distance from the centre; are constants. Then the charge density inside the ball is
As we learnt in
Gauss's Law -
Total flux linked with a closed surface called Gaussian surface.
Formula:
- wherein
No need to be a real physical surface.
Q_{enc} - charge enclosed by closed surface.
Electric field - (i)
change density inside the ball is
Option 1)
This is incorrect option
Option 2)
This is incorrect option
Option 3)
This is incorrect option
Option 4)
This is correct option
Two identical charged spheres suspended from a common point by two massless strings of length are initially a distance apart because of their mutual repulsion. The charge begins to leak from both the spheres at a constant rate. As a result the charges approach each other with a velocity . Then as a function of distance between them
Option 1 ans
A resistor capacitor in series is connected through a switch to direct supply. Across the capacitor is a neon bulb that lights up at Calculate the value of to make the bulb light up after the switch has been closed.
A fully charged capacitor with initial charge is connected to a coil of self inductance at The time at which the energy is stored equally between the electric and the magnetic fields is
A boat is moving due east in a region where the earth’s magnetic field is 5.0 × 10^{-5} N A^{-1} m^{-1} due north and horizontal. The boat carries a vertical aerial 2 m long. If the speed of the boat is 1.50 m s^{-1} , the magnitude of the induced emf in the wire of aerial is
1 mV
0.75 mV
0.50 mV
0.15 mV
Two bodies of masses are placed at a distance . The gravitational potential at a point on the line joining them where the gravitational field is zero is
An object moving with a speed of is decelerated at a rate given by
where is the instantaneous speed. The time taken by the object, to come to rest, would be
A water fountain on the ground sprinkles water all around it. If the speed of water coming out of the fountain is , the total area around the fountain that gets wet is
A car is fitted with a convex side-view mirror of focal length 20 cm. A second car 2.8 m behind the first car is overtaking the first car at a relative speed of 15 m s^{-1}. The speed of the image of the second car as seen in the mirror of the first one is
Let the plane be the boundary between two transparent media. Medium 1 in has a refractive index of and medium 2 with has a refractive index of . . A ray of light in medium 1 given by the vector is incident on the plane of separation. The angle of refraction in medium 2 is
Direction : The question has a paragraph followed by two statements, Statement-1 and Statement-2. Of the given four alternatives after the statements, choose the one that describes the statements.
A thin air film is formed by putting the convex surface of a plane-convex lens over a plane glass plate. With monochromatic light, this film gives an interference pattern due to light reflected from the top (convex) surface and the bottom (glass plate) surface of the film.
Statement - 1: When light reflects from the air- glass plate interface, the reflected wave suffers a phase change of .
Statement - 2: The centre of the interference pattern is dark.
Statement-1 is true, Statement-2 is false.
Statement-1 is true , Statement-2 is true, Statement-2 is the correct explanation of Statement-1.
Statement-1 is true, Statement-2 is true, Statement-2 is not the correct explanation of Statement-1.
Statement-1 is false, Statement-2 is true.
A mass attached to a horizontal spring, executes with a amplitude When the mass passes through its mean position then a smaller mass is placed over it and both of them move together with amplitude . The ratio of is
The transverse displacement of a wave on a string is given by
This represents a
Two particles are executing simple harmonic motion of the same amplitude A and frequency along the -axis. Their mean position is separated by distance . If the maximum separation between them is , the phase difference between their motion is
Work done in increasing the size of a soap bubble from a radius of 3 cm to 5 cm is nearly ( Surface tension of soap solution = 0.03 N m^{-1})
Water is flowing continuously from a tap having an internal diameter 8 × 10^{-3} m . The water velocity as it leaves the tap is 0.4 m s^{-1} . The diameter of the water stream at a distance 2 × 10^{-1} m below the tap is close to
5.0 × 10^{-3} m
7.5 × 10^{-3} m
9.6 × 10^{-3} m
3.6 × 10^{-3} m
The half life of a radioactive substance is 20 minutes. The approximate time interval between the time when of it has decayed and time when of it had decayed is