Kepler’s second law regarding constancy of arial velocity of a planet is a consequence of the law of conservation of
Food gets cooked faster in a pressure cooker because
Consider the following statements and select the correct code.
Assertion (A): A stick is dipped in water in a slanting position. If observed sideways, the stick appears short and bent at the surface of water.
Reason (R): The light coming from the stick undergoes scattering from water molecules giving the stick a short and bent appearance.
A convex and a concave lens seperated by distance d are then put in contact. The focal length of the combination
Magnetism at the centre of a bar magnet is
A horizontal metal wire is carrying an electric current from the north to the south. Using a uniform magnetic field, it is to be prevented from falling under gravity. The direction of this magnetic field should be towards the______.
A player making a long jump is an example of?
Of the following properties of a wave, the one that is independent of the other is its
A body projected vertically from the earth reaches a height equal to earth's radius before returning to the earth. The power exerted by the gravitational force is greatest
An observer is moving with half the speed of light towards a stationary microwave source emitting waves at frequency 10 GHz. What is the frequency of the microwave measured by the observer?
(speed of light = 3 × 108 ms–1)
Rectifiers are used to convert
The period of a satellite in a circular orbit of radius R is T. The period of another satellite in circular orbit of radius 4R is
Light from the Sun reaches us in nearly
The resistance of an incandescent lamp is
A piece of ice is floating in a beaker containing water. When whole of the ice melts
A time dependent force F = 6t acts on a particle of mass 1 kg. If the particle starts from rest, the work done by the force during the first 1 sec. will be :
On a rainy day, small oil films on water show brilliant colours. This is due to
When a temperature rises, the drift velocity of the free electrons decreases. Hence for given applied voltage?
During a thunderstorm, the thunder in the sky is produced by the
1. meeting of cumulonimbus clouds in the sky
2. lightning that separates the nimbus clouds
3. violent upward movement of air and water particles
Select the correct answer using the codes given below.
A copper ball of mass 100 gm is at a temperature T. It is dropped in a copper calorimeter of mass 100 gm, filled with 170 gm of water at room temperature. Subsequently, the temperature of the system is found to be 75°C. T is given by : (Given : room temperature = 30° C, specific heat of copper = 0.1 cal/gm°C
Consider the following statements and select the correct code.
Assertion (A): The velocity of sound in air increased due to the presence of moisture in it. Reason (R): The presence of moisture in air lowers the density of air.
Rainbow is formed due to a combination of
The distance between centre of the earth and moon is 384000 km. If the mass of the earth is 6 ´ 1024 kg and G = 6.66 ´ 10-11 Nm2/kg2. The speed of the moon is nearly
Which instrument is used to measure strength of direct current ?
The resistivity of a wire depends on its
The temperature of a gas contained in a closed vessel of constant volume increases by 1°C when the pressure of the gas is increased by 1%. The initial temperature of the gas is ______.
The nuclear reaction in which a heavy nucleus splits into two nuclei of nearly equal mass is called