List of top Questions asked in DUET

A square wire frame of size $L$ is dipped in a liquid. On taking out, a membrane is formed. If the surface tension of liquid is $T$, the force acting on the frame will be :

The frequency of a light ray is $ 6\times {{10}^{4}}\,\,Hz $ . Its frequency when it propagates in a medium of refractive index $1.5$, will be:

The electrical permittivity and magnetic permeability of free space are respectively $ {{\varepsilon }_{o}} $ and $ {{\mu }_{0}} $ . The corresponding value for a medium is:

A man of weight $80\, kg$ is standing in an elevator which is moving with an acceleration of $ 6\,m/{{s}^{2}} $ in upward direction. The apparent weight of the man will be $ (g=10\,\,m/{{s}^{2}}) $ :

In germanium crystal, the. forbidden energy gap in joule is :

The current gain of a transistor in common emitter mode is $49$. The change in collector current and emitter current corresponding to the change in base current by $5.0 \,\mu A, $ will be

An electron moves in a circular path of radius $15 \,cm$ in a magnetic field of intensity $ B=4\times {{10}^{-4}}\,T $ . The velocity of electron is :

What is the value of linear velocity, if angular velocity is $3 \hat{ i }-4 \hat{ j }+\hat{ k }$ and distance from the centre is $5 \hat{ i }-6 \hat{ j }+6 \hat{ k }$ ?

The magnetic moment of a magnet of length $10 \,cm$ and pole strength $4.0\, Am $ will be:

Two point charges $ 3\times {{10}^{-6}}C $ and $ 8\times {{10}^{-6}}C $ repel each other by a force of $ 6\times {{10}^{-3}}N $ . If each of them is given an additional charge $ -6\times {{10}^{-6}}C $ , the force between them will be:

A point source of light S, placed at a distance L in front of the centre of a plane mirror of width d, hangs vertically on a wall. A man walks in front of the mirror along a line parallel to the mirror at a distance 2L from it as shown. The greatest distance over which he can see the image of the light source in the mirror is