NEET 2019

Which of the following acts as a circuit protection device ?

In which of the following devices, the eddy current effect is not used ?

Two similar thin equi-convex lenses, of focal length f each, are kept coaxially in contact with each other such that the focal length of the combination is $$F_1$$. When the space between the two lenses is filled with glycerin (which has the same refractive index $$(\mu = 1.5)$$ as that of glass) then the equivalent focal length is $$F_2$$. The ratio $$F_1 : F_2$$ will be:

The unit of thermal conductivity is:

Pick the wrong answer in the context with rainbow.

Body A of mass 4m moving with speed u collides with an other body B of mass 2m, at rest. The collision is head on and elastic in nature. After the collision the fraction of energy lost by the colliding body A is :

Ionized hydrogen atoms and $$\alpha -$$ particles with same momenta enters perpendicular to a constant magnetic field, B. The ratio of their radii of their paths $$r_H : r_{\alpha}$$ will be:

A particle moving with velocity $$\overrightarrow{V}$$ is acted by three forces shown by the vector triangle PQR. The velocity of the particle will:

For a p-type semiconductor, which of the following statements is true ?

A cylindrical conductor of radius R is carrying a constant current. The plot of the magnitude of the magnetic field, B with the distance, d, from the centre of the conductor, is correctly represented by the figure :