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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,... 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.... 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... 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)... View Article

The value of stopping potential in thefollowing diagram

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

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... View Article

The correct curve between the stoppingpotential (V) and intensity of incidentlight (I) is

Stopping potential does not depend upon intensity of incident light (I).

Which one of the following materials cannot be used as a lightning rod?

As wood is not a conductor, it does not allow the flow of charges through it. Hence, we cannot use it... View Article

The instrument which records waves on the surface of the earth produced by tremors is called

Seismograph, an instrument that makes a record of seismic waves caused by an earthquake, explosion, or another Earth-shaking phenomenon. The tremors produce a... View Article

The curve between current (i) and potential difference (V) for a photo cell willbe

In photocell, at a particular negativepotential (stopping potential V0) of anode, photoelectric current is zero, At the potential difference between... View Article

TwoPN-junctions can be connected in series by three different methods as shown in the figure. If the potential difference in the junctions is the same, then the correct connections will be [IIT-JEE 1989]

Because in case (1) N is connected with N. This is not a series combination of transistor.

The core of a transformer islaminated to reduce energy losses due to[CBSE PMT 1990; Karnataka CET (Med.) 2001]

Circulation of eddy currents is prevented by use of laminated core.

The stoppingpotential as a function of the frequency of the incident radiation is plotted for two different photoelectric surfaces A and B. The graphs show that work function of A is

From the given graph it is clear that if we extend the given graph for A and B, intercept of... View Article

In Young’s double slit experiment, if the two slits areilluminated with separate sources, no interference pattern is observed because

In conventional light source, light comes from a large number of independent atoms, each atom emitting light for about 10-9... View Article

Theozone layer absorbs[Kerala PET 2002]

Ozone layer absorbs most of the UV rays emitted by sun.

The equivalent quantity of mass in electricity is

Inductance is inherent property of electricalcircuits. It will always be found in an electrical circuit whether we want it or... View Article

Anelectric dipole is kept in non-uniform electric field. It experiences [AIIMS 2003; DCE 2001]

As the dipole will feel two forces which are although opposite but not equal. A net force will be there... View Article

Inan insulator, the forbidden energy gap between the valence band and conduction band is of the order of[DPMT 1988; EAMCET (Engg.) 1995; MP PET 1996]

In insulators, the forbidden energy gap is largest and it is of the order of 6 eV

Which of the following is most suitable for the core of electromagnets? A) Air B) Steel C) Soft iron D) Copper-Nickel alloy

The correct option is C) Soft iron. Soft iron is selected for making the core of an electromagnet because the... View Article

A conducting wire is moving towards right in amagnetic field B. The direction of induced current in the wire is shown in the figure. The direction of magnetic field will be

According to Fleming right hand rule, the direction of B will be perpendicular to the plane of paper and act... View Article

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