NEET 2018

The fundamental frequency in an open organ pipe is gers eeeea closed organ pipe.If the length of a closed organ pipe is 20 cm , then the length of closed organ pipe is

The efficiency of an ideal heat) engine working between the freezing point and boiling point of water,is

At what temperature will the rms speed of oxygen molecules become just sufficient for escaping from the; Earth’s atmosphere ?
(Given : Mass of oxygen molecule $$(m) = 2.76 \times 10^{-26} kg)$$
Boltzmann's constant $$k_{B}=1.38 \times 10^{-23} J K^{-1}$$

Unpolarised light is incident from air on a plane surface of a material of refractive index $$\mu$$. At a particular angle of incidence ‘i’, it is found that the reflected and refracted rays are perpendicular to each other. Which of the following options is correct for this situation ?

In Young’s double slit experiment the separation d between the slits is 2 mm, the wavelength $$\lambda$$ of the light used is 5896 A and distance D between the screen and slits is 100 cm.It is found that the angular width of the fringes is $$0-20^\circ$$ To increase the fringe angular width to $$0.21^\circ$$ (with same $$\lamda$$ and D) the seaparation between the slits needs to be changed to

An astronomical, refracting telescope will have large angular magnification and high angular resolution, when it has an objective lens of

In the circuit shown in the figure, the input voltage $$v_{i}$$ is 20 V , $$V_{BE}$$=0 and $$V_{CE}$$=0 The values of $$I_{B},I_{C},\beta$$ are given by

In a p-n junction diode, change in temperature dueto heating

In the combination of the following gates the output Y can be written in terms of inputs A and B as

A metallic rod of mass per unit length $$0.5 kg m^{-1}$$ is lying horizontally on a smooth inclined plane which makes an angle of $$30^\circ$$ with the horizontal. The rod is not allowed to slide down by flowing a current through it when a magnetic field of induction 0:25 T is acting on it in the vertical direction. The current flowing in the rod to keep it stationary is