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The waves used in telecommunication are

In telecommunication, microwaves are used. Telecommunication refers to the process of exchange of information by using electronic devices over a... View Article

Choose the correct answer regarding luminous objects: Statement 1: Objects which emit light on their own are known as luminous objects Statement 2: Luminous objects are responsible for our vision Statement 3: Candle and earth are examples of luminous objects Statement 4: luminous objects reflect and emit light

Answer: Statement 1, 2 and 4 are correct Objects that emit their own light are called luminous objects. The human eye perceives the light... View Article

The law, governing theforce between electric charges is known as [CPMT 1972; MP PMT 2004]

Coulomb's law is used to calculate the force between charges.... View Article

The lower portion of clouds are negatively charged, what effect would it have on the earth?

This is charging by induction. The negative charges attract the opposite (positive) charge towards them.... View Article

Light from sodium lamp is passedthrough cold sodium vapours, the spectrumof transmitted light consists of [MP PET 1989; RPMT 2001]

According to Kirchhoff's law, a substance in unexcited state will absorb these wavelength which it emits in de-excitation.... View Article

Fraunhofer lines are obtained in [CPMT 1973; MP PMT 1989; MP PMT 2004]

The black lines in the solar spectrum are called Fraunhofer lines. The elements in the outer atmosphere (chromosphere) of the Sun absorb the... View Article

Choose the right answer from the following

We use flint glass prism to disperse polychromatic light because light of different colours: Travel with same speed Travel with same speed... View Article

What do you understand by the gravitational force of earth and weight?

Weight:The force... View Article

Iftwo streams of protons move parallel to each other in the same direction, then they[MP PET 1999; AIIMS 2004]

For charge particles, if they are moving freely in space, electrostatic force is dominant over magnetic force between them. Hence due to electric... View Article

A conducting circularloop of radius r carries a constant current i. It is placed in a uniform magnetic field , such that is perpendicular to the plane of the loop. The magnetic force acting on the loop is[BIT 1992; MP PET 1994; IIT 1983;MP PMT 1999; AMU (Engg.) 2000]

Net force on a current carrying closed loop is always zero, if it is placed in an uniform magnetic field.... View Article

Which of the following object is luminous?

Luminous objects have their own light. Light is produced/comes from luminous objects which is responsible for our vision. Ex- Stars, Torch... View Article

If you are given with a force of magnitude 25 N acting on a body of mass 2 kg increases its kinetic energy from 100 J to 200 J. The displacement of the body during this interval is

Work done by the force would be equal to the change in kinetic energy of the body. The change in kinetic energy is equal to 100 J and we know... View Article

If the distance between the objects increase, mass remaining same then the gravitational forces between the objects will :-

Gravitational force is given by F=GMm/r2 That implies... View Article

Total internal reflection oflight is possible when light enters from [CPMT 1973; MP PMT 1994]

For total internal reflection light must travel from denser medium to rarermedium. ... View Article

Two identical circular loops of metal wire are lying ona table without touching each other. Loop-A carries a current which increases with time. In response, the loop-B [IIT JEE 1999; UPSEAT 2003]

If the current increases with time in loop A, then magnetic flux in B will increase. According to Lenz's law, loop -B is repelled by loop -A. ... View Article

Choose the incorrect statement regarding wind power: (a) It is expected to harness wind power to maximum and not minimum in open spaces (b) The source of wind power is the potential energy content of the wind blowing at high altitudes (c) The rotation of the blades is possible when the wind hits them (d) Wind energy is used in running the turbine of an electric generator

The correct option is (a) It is expected to harness wind power to maximum and not minimum in open spaces. Wind power is the conversion of wind... View Article

An electron moves along the line AB, which lies in the same plane as acircular loop of conducting wires as shown in the diagram. What will be the direction of current induced if any, in the loop [MP PET 1989; AIIMS 1982, 2001; KCET 2003; UPSEAT 2005]

If electron is moving from left to right, the flux linked with the loop (which is into the page) will first increase and then decrease as the... View Article

A radioactive sampleconsists of two distinct species having equal number of atoms initially. The mean life time of one species is t and that of the other is 5t. The decay products in both cases are stable. A plot is made of the total number of radioactive nuclei as a function of time. Which of the following figures best represents the form of this plot[IIT-JEE (Screening) 2001]

The total number of atoms neither remains constant (as in option (a) nor can ever increase (as in option (b) and (c)). They will continuously... View Article

The value of stopping potential in thefollowing diagram

Stopping potential is that negative potential for which photo electric current is zero.... View Article

In the case ofconstants a and b of a transistor [CET 2003]

a is the ratio of collector current and emitter current while b is the ratio of collector current and base current.... View Article

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