Which of the following acts as a circuit protection device ?
In which of the following devices , the eddy current effect is not used ?
magnetic braking in train
Pick the wrong answer in the context with rainbow
When the light rays undergo two internal reflection in a water drop , a secondary rainbow is formed
The order of colors is reversed in the secondary rainbow
An observer can see a rainbow when his front is towards the sun
Rainbow is a combined effect of dispersion , refreaction and reflection of sunlight
A particle moving with velocity is acted by three forces shown by the vector triangle PQR . The velocity of the particle will :
change acording to the smallest force QR
Two parallel infinite line charges with linear charges densities are placed at a distance of 2R in free space . what is the electric field mid way between the two line charges ?
Two similar thin equiconvex lenses , of focal length f each , are kept coaxially in contact with each other such that the focal length of the combination is . When the space between the two lenses is filled with glycerin then the equivalent focal length is . The ratio
2 : 1
1 : 2
2 : 3
3 : 4
The total energy of an electron in an atom in an orbit is -3.4 eV . Its kinetic and potential energies are respectively
-3.4 e V, -3.4 eV
-3.4 e V , - 6.8 e V
3.4 e V , - 6.8 e V
3.4 e V , 3.4 e V
A soap bubble , having radius of 1 mm is blown from, a detergent solution having a surface tension , of . The pressure inside the bubble equals at a point below the free surface of water in a container of water = , the value of is
The unit of thermal conductivity is :
A parallel palte capacitor of capacitance is being charged by a voltage source whose potential is changing at the rate of 3 V/s . The conduction current through the connecting wires , and the dispalcement current through the plates of the capacitor , would be resectively :
zero , zero
When a object is shot from the bottom of a long smooth inclined plane kept at an angle with horizontal , it can travel a distance along the plane . But when the inclination is decreased to and the same object is shot with the same velocity , it can travel
A small hole of area of cross sectyion is present mear the botom of a fully filled open tank of heiht 2 m . Taking , the rate of flow of water through the open hole would be nearly :
A disc of radius 2 m and mass 100 Kg rolls on a horizontal floor . Its center of mass has speed of 20 cm/s . How much work is needed to stop it ?
A force F = 20 + 10 y acts on a particle in y - direction where F is in newton and y in meter Work done by this force to move the particle from y = 0 to y = 1 is :
A body weighs 200 N on the surface of the earth how much will it weigh at half way down to the center of the earth ?
Body A of mass 4m moving with speed u colloides with another body B ofmass 2m , at rest . The collision is head on and elastic in nature . After the colloision the fraction of energy lost by the colliding body A is :
particle constist of :
2 protons and 2 nuetrons only
2 electrons , 2 protons and 2 nuetrons
3 electrons and 4 protons
2 protons only
Two point charges A and B , having charges Q and - Q respectively , are placed at a certain distance apart ad force acting between them is F . If 25 % charge of A is transferres to B , then force between he charges becomes :
In total internal reflection when the angle of incidende is equal to the critical angle for the pair of media in contact what will be angle of refraction ?
equal to angle of incidence
The work done to raise a mass m from the surface of the earth to a height h, which is equal to the radius of the earth is :